[Feature Request] Google Service Accounts instead of Auth Token

[Skyfay]

I think it would be very cool if Plexdrive would also support service accounts.
I've had problems with tokens lately and there aren't any with the service accounts.
Rclone support Service Accounts:

Service Account Credentials JSON file path.

Leave blank normally. Needed only if you want use SA instead of interactive login.

Leading ~ will be expanded in the file name as will environment variables such as ${RCLONE_CONFIG_DIR}.

Properties:

Config: service_account_file
Env Var: RCLONE_DRIVE_SERVICE_ACCOUNT_FILE
Type: string
Required: false```