* fix(two-factor-controller) [PM-24211]: Update send email validation to use auth request's IsValidForAuthentication.
* refactor(login-features) [PM-24211]: Remove Core.LoginFeatures as no longer used; AuthRequest.IsValidForAuthentication should be used for any applicable use cases.
* feat(auth-request) [PM-24211]: Add tests for AuthRequest.IsValidForAuthentication.
* fix(two-factor-controller) [PM-24211]: Branching logic should return on successful send.
* chore(auth-request) [PM-24211]: Remove some old comments (solved-for).
* fix(two-factor-controller) [PM-24211]: Update some comments (clarification/naming).
* fix(two-factor-controller) [PM-24211]: Rephrase a comment (accuracy).
