Add ignored files to GHA steep summary.

[sarahchen6]

What does this PR do?
Add ignored files from Steepfile into our GHA steep/typecheck summary. Here is an example of a steep/typecheck summary.

Motivation:
We have a lot of files that are ignored by steep type-checking, so this will provide visibility in our summary of which files are ignored.

Change log entry
None.

Additional Notes:

How to test the change?
See the ignored files in the GHA steep/typecheck summary for this PR.

[datadog-datadog-prod-us1]

Datadog Report

Branch report: sarahchen6/add-ignored-files-to-steep-summary
Commit report: 0b29186
Test service: dd-trace-rb

✅ 0 Failed, 20611 Passed, 1373 Skipped, 3m 21.14s Total Time

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.69%. Comparing base (fa88415) to head (0b29186).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4439      +/-   ##
==========================================
- Coverage   97.71%   97.69%   -0.02%     
==========================================
  Files        1374     1374              
  Lines       83755    83806      +51     
  Branches     4236     4249      +13     
==========================================
+ Hits        81841    81877      +36     
- Misses       1914     1929      +15     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2025-02-28 17:09:06

Comparing candidate commit 0b29186 in PR branch sarahchen6/add-ignored-files-to-steep-summary with baseline commit fa88415 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 31 metrics, 2 unstable metrics.

[p-datadog]

If a file is given in steepfile but does not exist on the filesystem, will it be shown in the report?

[sarahchen6]

If a file is given in steepfile but does not exist on the filesystem, will it be shown in the report?

It will be shown in the report, but that's a good situation to highlight. Just added - If the file does not exist in the filesystem, then a warning about the missing file and a recommendation to remove it from Steepfile is given, instead of it being added to the report.

[lloeki]

Approved!