Notification emails for impersonation tokens

Problem to solve

The creator of a Personal Access Token (PAT) receives an email notification when that Token is expiring, except for impersonation Tokens. They should be notified about impersonation Tokens too.

Proposal

Creators of "impersonation tokens" (a type of Personal Access Token) should receive an email notification when these Tokens are expiring. (The impersonated users should not receive an email.)

Further details

PAT expiration notification emails were implemented in MR !19296 (merged) and included impersonation Tokens at that time. These emails were disabled for impersonation Tokens due to the bug described in Issue #216103 (closed). This issue needs to restore those emails, but with logic that ensures they are sent to the creator and not the impersonated user.