[DPE-6752] Implement instance level predefined roles

[shayancanonical]

Issue

VM PR 881 introduces a change to implement instance level predefined roles. These changes, along with updates to the postgresql charmlib, need to be ported over to this repository.

Solution

Port over implementation

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[codecov]

Codecov Report

Attention: Patch coverage is 39.13043% with 14 lines in your changes missing coverage. Please review.

Project coverage is 71.91%. Comparing base (4ce6826) to head (f301d6f).

Files with missing lines	Patch %	Lines
src/charm.py	50.00%	6 Missing ⚠️
src/upgrade.py	14.28%	6 Missing ⚠️
src/relations/postgresql_provider.py	33.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           16/edge     #970      +/-   ##
===========================================
- Coverage    72.16%   71.91%   -0.25%     
===========================================
  Files           14       14              
  Lines         3693     3707      +14     
  Branches       525      526       +1     
===========================================
+ Hits          2665     2666       +1     
- Misses         829      841      +12     
- Partials       199      200       +1     

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[marceloneppel]

Latest changes also LGTM! Thanks for bumping the library to V1. This way, we can avoid legacy code in the new PG 16 codebase.