[do not merge] Only mark frame as in_app if explicitly set by user

[sentrivana]

❗ This is ready for review, but not ready to be merged. Releasing this needs to be coordinated with (1) the SDK sending project_root (#3941) and (2) the logic actually being moved to the server.

Only take in_app_include and in_app_exclude into account when marking a frame in_app, nothing else. The existing logic will be moving to the server. We will not merge this before that happens.

See getsentry/sentry#83603 for the big picture

Closes #3945

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.18%. Comparing base (48d6368) to head (df19ad8).
Report is 181 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3984      +/-   ##
==========================================
- Coverage   80.20%   80.18%   -0.03%     
==========================================
  Files         139      139              
  Lines       15394    15385       -9     
  Branches     2596     2593       -3     
==========================================
- Hits        12347    12336      -11     
- Misses       2202     2203       +1     
- Partials      845      846       +1     

Files with missing lines	Coverage Δ
sentry_sdk/utils.py	83.29% <ø> (-0.43%)	⬇️

... and 2 files with indirect coverage changes

[lobsterkatie]

LGTM. One question below, and one which I couldn't put in the right spot because it's not near enough to a change, which is:

        # if frame has already been marked as in_app, skip it
        current_in_app = frame.get("in_app")
        if current_in_app is not None:
            continue

How is it that a frame could come in with an in-app value already set?

[lobsterkatie]

This actually partially answers a question I had, which is how windows paths get reported. Is it safe to assume that if the paths in the frames are reported with the C: and with double backslashes, the project root will be, too?

[sentrivana]

I'd guess so -- if the two didn't match then the is-in-project-root check would never be correct.

[sentrivana]

How is it that a frame could come in with an in-app value already set?

I am not sure, which is why I opted for not changing it. It shouldn't hurt in any case.