User settings improvements
This issue contains a list of things to improve in user settings area.

- [x] Add user email verification (via server email settings)
- [x] <strike>Possibly discourage the possibility of admin changing other user's passwords</strike> Not needed
- [x] <strike>Add user invite links, with ability for the user to enter their password after entering that link</strike> Not sure why is it even needed
- [x] Add change password functionality for non-server admins
- [x] Add 2FA support
- [x] Add webauthn support
- [x] <strike>Add ability for shared access, for some user to give a read/write access to their stores, and special filters in admin panel to filter between your own stores and other user's stores</strike> Moved to #329

