chore: adds well-defined reason to non hotswappable resources

[mrgrain]

This is in preparation of making the value available in a structured message to the IoHost.

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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 87.50000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 85.07%. Comparing base (db4029c) to head (ff953f2).

Files with missing lines	Patch %	Lines
...aws-cdk/lib/api/deployments/hotswap-deployments.ts	73.68%	5 Missing ⚠️
packages/aws-cdk/lib/api/hotswap/common.ts	90.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #252      +/-   ##
==========================================
- Coverage   85.11%   85.07%   -0.05%     
==========================================
  Files         218      218              
  Lines       36517    36548      +31     
  Branches     4584     4570      -14     
==========================================
+ Hits        31082    31093      +11     
- Misses       5289     5310      +21     
+ Partials      146      145       -1     

Flag	Coverage Δ
suite.unit	85.07% <87.50%> (-0.05%)	⬇️

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[mrgrain]

applied exemption label because a previous run passed