Detekt the api coverage in Integration tests

[xgouchet]

What does this PR do?

This updates how we compute our API coverage through Integration tests, by ignoring methods flagged with @Internal and Extension methods we use for non Datadog classes.

Motivation

Improve our visibility on integration test coverage

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.25%. Comparing base (21025fd) to head (6d6ea18).
Report is 30 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2300      +/-   ##
===========================================
- Coverage    70.44%   70.25%   -0.19%     
===========================================
  Files          730      730              
  Lines        27268    27265       -3     
  Branches      4584     4584              
===========================================
- Hits         19207    19153      -54     
- Misses        6815     6830      +15     
- Partials      1246     1282      +36     

see 25 files with indirect coverage changes