Tests: Add coverage for WP_Recovery_Mode.
Test recovery mode initialization, error handling, recovery emails, plugin and theme error storage, redirects, session exit, and expired-key cleanup. Cover filter behavior and invalid inputs, and isolate tests that depend on headers or process state.
Developed in: https://github.com/WordPress/wordpress-develop/pull/14160
Props huzaifaalmesbah.
See #65819.
Javascript required