Add "caused by" section(s) when forwarding logs

[jtduffy]

Resolves #1189

This change will add the caused by portion of a stack trace, if available, when decorating logs for forwarding. Note that the maximum stack trace size of 300 is still enforced so stack traces can still be truncated. Added unit tests to verify the new functionality.

This logic is same used when generating stack traces for TracedErrors/ErrorEvents.

Changed instrumentation:

• log4j1
• log4j2
• logback
• JUL

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.77%. Comparing base (0e3a23f) to head (ddfb068).
Report is 23 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1857      +/-   ##
============================================
- Coverage     70.88%   70.77%   -0.11%     
+ Complexity     9974     9852     -122     
============================================
  Files           829      821       -8     
  Lines         39985    39694     -291     
  Branches       6058     6049       -9     
============================================
- Hits          28344    28095     -249     
+ Misses         8915     8874      -41     
+ Partials       2726     2725       -1     

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