Pressing the user settings button brings up a list of all jellyfin
users, and allows you to add or change their stored email addresses.
Additionally, changed emails.json to use user ID instead of username.
The program automatically converts the file to the new format at start.
The admin page now has the option to send an invite to an email address.
Since there are now two email types (invites and pw resets), the new
sections have been added to config.ini, and email_template and
email_plaintext have been renamed to email_html and email_text
respectively.
Invites and the generate invite form are now displayed as cards. Invite
codes are displayed in a monospace font so they are always aligned with
eachother. The delete button is now inline with the rest of the text.
