Allow owner to authorize if it's their own consumer

* Show an error on the /authorize step if the consumer is not approved,
instead of waiting until the form was submitted to give an error.
* Except when the owner is authorizing this consumer

Similar to I0a3f624ea3a7b057eddfd4c2b8e63668462ab6aa

Change-Id: I10e7804d685f1d9f4fd8c2fe29adbfcf8dbd6cd0
Merge "Allow owner to authorize if it's their own consumer"