[SDTEST-755] attempt to fix datadog_cov crash when doing allocation profiling

[anmarchenko]

What does this PR do?
Fixes potential crash from the test impact analysis native extension when Object.const_source_location unexpectedly returns weird values. Adds more testing for these cases.

Motivation
We got reports of datadog_cov native extension crashes via telemetry crashtracker: while the root cause is unknown yet, this fix is an attempt to mitigate one of the possible causes

How to test the change?
Unit tests are provided

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.93%. Comparing base (af3db96) to head (58452e4).
Report is 15 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #224   +/-   ##
=======================================
  Coverage   98.92%   98.93%           
=======================================
  Files         261      262    +1     
  Lines       12391    12440   +49     
  Branches      560      560           
=======================================
+ Hits        12258    12307   +49     
  Misses        133      133           

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