Instead of using a separate function to force logging out before
login, login now has a boolean parameter that instructs it to logout
before loging in again, if the user is alread logged in. It then
starts the authorization with a force browser logout first.
CURA-7427
There are cases where Cura and the browser fall out of sync when it
comes to accounts. In such cases, you may be logged in cura with an
account that has no cloud printers and in the browser with an account
that has printers. So when you press the "Add cloud printer" button,
you are redirected to mycloud and you see cloud printers that are not
detected by Cura (because Cura is in a different acconut). In such
cases, the user can now press the "Sign in with a different account"
link in the "Waiting for cloud response" page, which will log him/her
out in Cura AND in the browser, and then reinitiate the whole
authorization flow, to make sure the accounts are in sync.
CURA-7427
Properly close the welcome screen if the user has signed in and has
cloud printers linked to his/her account. If he doesn't have any, move
to the next page of the welcome wizard.
CURA-7019
The new client has access to more permissions and is labeled as "Ultimaker Cura" instead of "Cura Backups Plugin".
Also removes `self._cloud_api_root` as that's not used anymore now that `self._oauth_root` is used for the redirect URLs.