[ENH] Add get_cache_size Utility Function

[JATAYU000]

Metadata

• Reference Issue: Fixes [ENH] Add Cache Size Utility Function #1561
• New Tests Added: Yes
• Documentation Updated: Yes (Doc string)
• Change Log Entry: Add new function get_cache_size() in utils

Details

• What does this PR implement/fix?
  Implements a get_cache_size() function which returns the total size of the openml cache directory in bytes.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.77%. Comparing base (ef242af) to head (a25c333).

Files with missing lines	Patch %	Lines
openml/utils.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1565      +/-   ##
==========================================
- Coverage   52.78%   52.77%   -0.02%     
==========================================
  Files          36       36              
  Lines        4357     4360       +3     
==========================================
+ Hits         2300     2301       +1     
- Misses       2057     2059       +2     

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[fkiraly]

@geetu040 please review

[geetu040]

Looks fine. And this will not conflict with migration config, so good to go.