feat: Implement List Repository Activities endpoint

[AbhishekAg]

Fixes: #3649.

This PR implements support for the "List repository activities" REST API endpoint introduced in GitHub API v2022-11-28. This functionality allows go-github users to retrieve detailed activity information for repositories.

Implementation Details

• Added RepositoryActivity struct to represent activity data returned by the API
• Created ListRepositoryActivitiesOptions for pagination and filtering options (direction, before/after timestamps)
• Implemented ListActivities method in the RepositoriesService
• Added comprehensive tests for the new functionality
• Updated documentation with usage examples

API Reference
This implementation follows the GitHub REST API specification documented at:
https://docs.github.com/en/rest/repos/repos?apiVersion=2022-11-28#list-repository-activities
Example Usage

opts := &github.ListRepositoryActivitiesOptions{
Direction: "desc",
After: "2023-01-01T00:00:00Z",
ListOptions: github.ListOptions{
Page: 1,
PerPage: 30,
},
}
activities, resp, err := client.Repositories.ListActivities(ctx, "owner", "repo", opts)

Testing

The implementation includes unit tests that verify:

• Correct URL formatting and parameter handling
• Proper deserialization of API responses
• Edge cases (empty results, error handling)

[gmlewis]

Thank you, @AbhishekAg.
Please address these items, then we should be ready for a second LGTM+Approval from any other contributor to this repo before merging.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.25%. Comparing base (9f2b91b) to head (a90671a).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #3651 +/- ##
=======================================
Coverage 91.25% 91.25% =======================================
Files 184 184 Lines 16311 16327 +16 =======================================
+ Hits 14884 14900 +16 
Misses 1245 1245 Partials 182 182 

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[gmlewis]

Thank you, @AbhishekAg!
LGTM.

Awaiting second LGTM+Approval from any other contributor to this repo before merging.

@stevehipwell or @alexandear - might one of you have time for a code review? Thank you!

[AbhishekAg]

@alexandear Please review the PR when you get time.

[AbhishekAg]

@gmlewis@alexandear Can you please push these changes to the protected branch? I am not allowed to perform the push.

[gmlewis]

Thank you, @alexandear!
Merging.