feat: Add Actions cache limits for repositories and enterprises

[bhuvaneshkumar-cyber]

Fixes #4645.

Adds the repository- and enterprise-level variants of the Actions cache retention/storage limit endpoints added for organizations in #4597, reusing the existing ActionsCacheRetentionLimit and ActionsCacheStorageLimit types.

AI disclosure: AI wrote the initial implementation and tests, following the existing org-level functions; I reviewed them and ran script/test.sh and script/lint.sh locally.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.62%. Comparing base (fef0352) to head (95adeab).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4646   +/-   ##
=======================================
  Coverage   98.61%   98.62%           
=======================================
  Files         199      199           
  Lines       18694    18750   +56     
=======================================
+ Hits        18436    18492   +56     
  Misses        258      258           

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[gmlewis]

Thank you, @bhuvaneshkumar-cyber!
LGTM.
Awaiting second LGTM+Approval from any other contributor to this repo before merging.