refactor: Move search functions and tests to their own files

[zkoppert]

Pull Request

This pull request refactors the issue_metrics.py module by moving the search_issues and get_owners_and_repositories functions to a new search.py module. Additionally, it moves the corresponding unit tests to their own test file to follow the current style.

The purpose of doing this is to improve readability of issue_metrics.py by separating out the search specific functions.

Proposed Changes

• Move search_issues and get_owners_and_repositories functions to search.py
• Move corresponding unit tests to `test_search.py
• Fix imports and pylint issues

Readiness Checklist

Author/Contributor

• If documentation is needed for this change, has that been included in this pull request
• run make lint and fix any issues that you have introduced
• run make test and ensure you have test coverage for the lines you are introducing
• If publishing new data to the public (scorecards, security scan results, code quality results, live dashboards, etc.), please request review from @jeffrey-luszcz

Reviewer

• Label as either fix, documentation, enhancement, infrastructure, maintenance, or breaking