Linting to reduce number of Fortitude exemptions

[Sam Clarke-Green (t00sa)]

PR Summary

Code Reviewer: R Sharp (@r-sharp)

Clean up the following Fortitude failures in shumlib:

Description	Code	Commit
missing-intent	C061	59ed1e8
initialisation-in-declaration	C081	b8da5d3
use-all	C121	ef778e3
unnamed-end-statement	S061	77250cc
old-style-array-literal	MOD011	98f9818
deprecated-relational-operator	MOD021	70c49e6
interface-implicit-typing	C002	2206195
missing-exit-or-cycle-label	C141	8e3cbb0

Status of remaining Fortitude exemptions:

Description	Justification	Action
implicit-external-procedures	Unimplemented Fortran 2018 feature	Leave in place
assumed-size	Complicated and linked with character intents	Create a separate PR
assumed-size-character-intent	See above	Same PR as above
syntax-error	Caused by preprocessor definitions	Leave in place

Note: missing-exit-or-cycle-label are not picked up with Fortitude 0.7.3 - the current default for LFRic - but they are picked up by the CI testing because it uses 0.7.5.

Code Quality Checklist

(Some checks are automatically carried out via the CI pipeline)

• I have performed a self-review of my own code
• My code follows the project's style guidelines
• Comments have been included that aid undertanding and enhance the
  readability of the code
• My changes generate no new warnings

Testing

• I have tested this change locally, using the rose-stem suite
• If any tests fail (rose-stem or CI) the reason is understood and
  acceptable (eg. kgo changes)
• I have added tests to cover new functionality as appropriate (eg. system
  tests, unit tests, etc.)

Shumlib regression suite runs through cleanly:

 Test module initialized

    . : successful assert,   F : failed assert 


Testing shum_constants at Shumlib version: 2025101
................................................
Testing shum_byteswap at Shumlib version: 2025101
.................................................................
Testing shum_string_conv at Shumlib version: 2025101
..............
Testing shum_wgdos_packing at Shumlib version: 2025101
.............................................................................................
Testing shum_thread_utils at Shumlib version: 2025101
...........................................................................................
Testing shum_latlon_eq_grids at Shumlib version: 2025101
........................................................................................................................................................................
Testing shum_fieldsfile at Shumlib version: 2025101
..............................................................................
..........................................................................................................................................
.......................................................................
Testing shum_horizontal_field_interp at Shumlib version: 2025101
.......................................................
Testing shum_spiral_search at Shumlib version: 2025101
........................
Testing shum_fieldsfile_class at Shumlib version: 2025101
....................................................................
Testing f_shum_number_tools at Shumlib version: 2025101
............................................................................................
Testing shum_kinds at Shumlib version: 2025101
........

     Start of FRUIT summary: 

 SUCCESSFUL!

   No messages 
 Total asserts :           1013
 Successful    :           1013
 Failed        :              0
Successful rate:   100.00%

 Successful asserts / total asserts : [         1013 /        1013  ]
 Successful cases   / total cases   : [          113 /         113  ]
   -- end of FRUIT summary
/var/tmp/persistent/Development/shumlib/build/meto-azspce-gfortran-gcc/tests/fruit_tests_dynamic.exe

 Test module initialized

    . : successful assert,   F : failed assert 


Testing shum_constants at Shumlib version: 2025101
................................................
Testing shum_byteswap at Shumlib version: 2025101
.................................................................
Testing shum_string_conv at Shumlib version: 2025101
..............
Testing shum_wgdos_packing at Shumlib version: 2025101
.............................................................................................
Testing shum_thread_utils at Shumlib version: 2025101
...........................................................................................
Testing shum_latlon_eq_grids at Shumlib version: 2025101
........................................................................................................................................................................
Testing shum_fieldsfile at Shumlib version: 2025101
..............................................................................
..........................................................................................................................................
.......................................................................
Testing shum_horizontal_field_interp at Shumlib version: 2025101
.......................................................
Testing shum_spiral_search at Shumlib version: 2025101
........................
Testing shum_fieldsfile_class at Shumlib version: 2025101
....................................................................
Testing f_shum_number_tools at Shumlib version: 2025101
............................................................................................
Testing shum_kinds at Shumlib version: 2025101
........

     Start of FRUIT summary: 

 SUCCESSFUL!

   No messages 
 Total asserts :           1013
 Successful    :           1013
 Failed        :              0
Successful rate:   100.00%

 Successful asserts / total asserts : [         1013 /        1013  ]
 Successful cases   / total cases   : [          113 /         113  ]
   -- end of FRUIT summary

Security Considerations

• This change does not introduce security vulnerabilities
• I have reviewed the code for potential security issues
• Sensitive data is properly handled (if applicable)
• Authentication and authorisation are properly implemented (if applicable)

Performance Impact

• Performance of the code has been considered and, if applicable, suitable
  performance measurements have been conducted

AI Assistance and Attribution

• Some of the content of this change has been produced with the assistance
  of Generative AI tool name (e.g., Met Office Github Copilot Enterprise,
  Github Copilot Personal, ChatGPT GPT-4, etc) and I have followed the
  Simulation Systems AI policy(including attribution labels)

Documentation

• Where appropriate I have updated documentation related to this change and
  confirmed that it builds correctly

Code Review

• All dependencies have been resolved
• Related Issues have been properly linked and addressed
• CLA compliance has been confirmed
• Code quality standards have been met
• Tests are adequate and have passed
• Documentation is complete and accurate
• Security considerations have been addressed
• Performance impact is acceptable

[R Sharp (r-sharp)]

Looks good to me.