* Onboarding: Invite new users
- Separates the user self-registration and invite cases
- Adds invitation email for users created by the admin
- Adds invitation tokens to verify user was invited
- Adds handler action for invite links
- Refactors `UserEventHostedService`
- Fixes#5726.
* Add permissioned form tag helper
* Better way of changing a user's role
* Test fixes
Fixes#5698. Before this, the app lookup was constrained by the user having at least `CanModifyStoreSettings` permissions. This changes it to require the user being associated with a store, leaving the fine-grained authorization checks up to the individual actions.
