* Don't delete the user's favorites unless private favorites are enabled. The general rule is that
public account activity is kept and private account activity is deleted.
* Delete the user's API keys, forum topics visits, private favgroups, downvotes, and upvotes (if
privacy is enabled).
* Reset all of the user's account settings to default. This means custom CSS is deleted, where it
wasn't before.
* Delete everything but the user's name and password asynchronously.
* Don't log the current user out if it's the owner deleting another user's account.
* Fix#5067 (Mod actions sometimes not created for user deletions) by wrapping the deletion process
in a transaction.
Move the account deletion endpoint from /maintenance/users/deletion to either:
* https://danbooru.donmai.us/users/deactivate
* https://danbooru.donmai.us/users/:id/deactivate
This incidentally allows the Owner-level user to deactivate accounts belonging to other users. This
is meant for things like deactivating inactive accounts with invalid or abusive names. This is
limited to accounts below Gold level for security.
