feat: Add flag to capture exceptions on futures in concurrent integration

[alexander-alderman-webb]

Provide the option to record when an exception is set on a Future returned by ThreadPoolExecutor.submit(). These were previously thrown only when result() is called on the future. Otherwise the exception is only stored on the future, and does not detected by the ThreadingIntegration despite concurrent using threading under the hood.

Closes #2614

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.67%. Comparing base (b397560) to head (7be052c).

Additional details and impacted files

@@                             Coverage Diff                             @@
##           webb/concurrent-integration-scopes-only    #4771      +/-   ##
===========================================================================
+ Coverage                                    84.65%   84.67%   +0.01%     
===========================================================================
  Files                                          159      159              
  Lines                                        16403    16414      +11     
  Branches                                      2811     2813       +2     
===========================================================================
+ Hits                                         13886    13898      +12     
+ Misses                                        1692     1691       -1     
  Partials                                       825      825              

Files with missing lines	Coverage Δ
sentry_sdk/integrations/concurrent.py	100.00% <100.00%> (ø)

... and 3 files with indirect coverage changes