Fix is_loaded_directly on nightly

[lgoettgens]

Resolves #2140.

We used to use the internal function Base.process_backtrace() that was changed in JuliaLang/julia#55841. This PR updates the code to instead use Base.stacktrace (which is public aka guaranteed to stay), but we now need to take care of kwcall ourselves.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.96%. Comparing base (e3a4248) to head (073c77c).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2141      +/-   ##
==========================================
- Coverage   87.97%   87.96%   -0.01%     
==========================================
  Files         126      126              
  Lines       31659    31671      +12     
==========================================
+ Hits        27851    27860       +9     
- Misses       3808     3811       +3     

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[lgoettgens]

Since CI is happy with this change, I am continuing to merge this to make CI green again. But please give this a review nonetheless when you are back from vacation. We can adapt things afterwards anyway.