Less Oracle, more cowb - er, Postgresql

[jas88]

Proposed Changes

Remove Oracle remnants, fill in some gaps in Postgresql support instead.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that would cause existing functionality to not work as expected)
• Documentation-Only Update (if none of the other choices apply)
  • In this case, ensure that the message of the head commit from the source branch is prefixed with [skip ci]

Checklist

By opening this PR, I confirm that I have:

• Reviewed the contributing guidelines for this repository
• Ensured that the PR branch is in sync with the target branch (i.e. it is automatically merge-able)
• Updated any relevant API documentation
• Created or updated any tests if relevant
• Created a news file
  • NOTE: This must include any changes to any of the following files: default.yaml, any of the RabbitMQ server configurations, GlobalOptions.cs
• Listed myself in the CONTRIBUTORS file 🚀
• Requested a review by the @SMI/Reviewers team

Issues

Partly addresses #1878

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 3 lines in your changes missing coverage. Please review.

Project coverage is 60.38%. Comparing base (7c407ff) to head (e216930).
Report is 17 commits behind head on main.

Files	Patch %	Lines
...per/Execution/Swappers/ForGuidIdentifierSwapper.cs	72.72%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1879      +/-   ##
==========================================
- Coverage   60.96%   60.38%   -0.59%     
==========================================
  Files         177      177              
  Lines        6559     6548      -11     
  Branches      898      898              
==========================================
- Hits         3999     3954      -45     
- Misses       2289     2327      +38     
+ Partials      271      267       -4     

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