Fix CLI allowing creation of access tokens with existing name (#26071)
We are now:
- Making sure there is no existing access token with the same name
- Making sure the given scopes are valid (we already did this before but
now we have a message)
The logic is mostly taken from
https://github.com/go-gitea/gitea/blob/a12a5f3652c339b17b187ff424a480631a3c1e1e/routers/api/v1/user/app.go#L101-L123
Closes #26044
Signed-off-by: Yarden Shoham <git@yardenshoham.com>
authored by