Re-added UUID as a fallback transaction ID

[jongpie]

Fixes #155 by reincorporating the UUID class as a secondary transaction ID in the event that System.Request.getCurrent().getRequestId() is null/blank.

So far, this seems to only occur within the context of Messaging.InboundEmailHandler, but the code is written so that a UUID value is used any time that the platform's request ID is null.

[codecov]

Codecov Report

Merging #170 (814ec12) into main (29d8e9b) will decrease coverage by 0.31%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #170      +/-   ##
==========================================
- Coverage   93.89%   93.57%   -0.32%     
==========================================
  Files          15       15              
  Lines        1866     1915      +49     
==========================================
+ Hits         1752     1792      +40     
- Misses        114      123       +9     

Impacted Files	Coverage Δ
...ebula-logger/main/logger-engine/classes/Logger.cls	90.69% <100.00%> (+0.69%)	⬆️
...management/classes/RelatedLogEntriesController.cls	90.13% <0.00%> (-5.93%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 29d8e9b...814ec12. Read the comment docs.