RUM-4418: Don't mark internal extension functions for 3rd party types as 3rd party

[0xnm]

What does this PR do?

Fix for the long-standing issue: UnsafeThirdPartyFunctionCall was marking internal extension functions for third-party types as third-party functions, which is wrong. This PR fixes that by checking the declaration package for the function in addition to its container.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[xgouchet]

Great work thanks

[codecov-commenter]

Codecov Report

Merging #1996 (9263a25) into develop (18967d7) will decrease coverage by 0.01%.
Report is 12 commits behind head on develop.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1996      +/-   ##
===========================================
- Coverage    83.66%   83.65%   -0.01%     
===========================================
  Files          488      488              
  Lines        17770    17730      -40     
  Branches      2663     2661       -2     
===========================================
- Hits         14867    14832      -35     
+ Misses        2178     2177       -1     
+ Partials       725      721       -4     

see 29 files with indirect coverage changes