Allow remote backups to be updated

[GentlemanHal]

Feature Request

What would you like to be able to do?
Make remote backup editable.

What problem would it solve?
Currently if anything changes a new remote backup needs to be added and the old one deleted.
Given it is good practice to have expiry dates on access tokens, it is likely remote backups to GitHub and GitLab would need to be updated from time to time.

This could work similar to updating Feeds.

As the access token is only stored encrypted it can't be pre-populated when editing.