fix/86: Display notice with vertices that cause a redirect cycle/loop

[Sidsector9]

Closes #86
Closes #87

Description of the Change

In PR #336, we use DFS to bring down the cycle detection time from O(n^2) to O(V+E). We also returned as soon as the first cycle was detected.

In this PR, we make small adjustments to record all detected cycles by not returning early and then display the "Redirect To" values that cause cycles in a warning notice.

This PR also sets the default value of the filter srm_check_for_possible_redirect_loops to true as there is no negative performance hit and also helps to detect a redirect loop during the time of creating redirects.

How to test the Change

1. Import the file srm-redirects-10000.csv. This file has 10,000 redirects.
2. Set the srm_max_redirects number to something more than 10,000.
3. Delete transients to gauge performance without it using wp transient delete --all
4. Visit /wp-admin/edit.php?post_type=redirect_rule

Changelog Entry

Changed - Include links to redirects that cause redirect loops/chains in the warning.
Changed - Set the default value for the srm_check_for_possible_redirect_loops filter to true.

Credits

Props @joshbetz @nicoladj77 @Sidsector9

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[ravinderk]

@Sidsector9 Can we add conflicted redirects with their editable page link in admin notices? In this way, the admin can view the redirect URL edit page instead of searching for them.