fix: Remove dependency on Serilog.Expressions.

[tippmar-nr]

BEGIN_COMMIT_OVERRIDE
fix: Remove dependency on Serilog.Expressions. Resolves #2083.
END_COMMIT_OVERRIDE

Description

Removes the dependency on the Serilog.Expressions package, which resolves issues experienced by some customers where the agent does not report data and does not create a log file.

Added a new log enricher for the required timestamp format in the log file. Updated existing log enrichers to improve performance where possible.

An integration test was added to validate that the logfile output is in the expected format.

Resolves #2083

Props to @chynesNR for sleuthing this one!

Author Checklist

• Unit tests, Integration tests, and Unbounded tests completed
• Performance testing completed with satisfactory results (if required)

Reviewer Checklist

• Perform code review
• Pull request was adequately tested (new/existing tests, performance tests)

[codecov-commenter]

Codecov Report

Merging #2082 (3b60d2d) into main (f8dcf18) will decrease coverage by 0.06%.
Report is 1 commits behind head on main.
The diff coverage is 85.71%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2082      +/-   ##
==========================================
- Coverage   81.11%   81.06%   -0.06%     
==========================================
  Files         395      395              
  Lines       24697    24695       -2     
  Branches     2966     2966              
==========================================
- Hits        20033    20019      -14     
- Misses       3882     3890       +8     
- Partials      782      786       +4     

Files	Coverage Δ
.../NewRelic/Agent/Core/Logging/LoggerBootstrapper.cs	78.48% <100.00%> (-0.27%)	⬇️
src/Agent/NewRelic/Agent/Core/Logging/AuditLog.cs	83.33% <50.00%> (ø)

... and 2 files with indirect coverage changes

[nr-ahemsath]

Looks good.