[13.x] Improve issuing PATs

[hafezdivandari]

This PR improves issuing personal access tokens:

• Reduces number of queries to retrieve the client from the DB from 3 to 1.
• Removes the necessity of redeclaring client credentials on passport.personal_access_client config property and environment variables for each user provider.
• Reorganizes personal access grant feature tests.
• Fully backward compatible and no upgrading steps is needed.

Before

After

Create a client using passport:client --personal for each user provider. Set client credentials on passport.personal_access_token config property for each user provider. Issue access token using $user->createToken(). Get client credentials for the given user provider from config. Retrieve the client from DB and validate provider. Pass client_id, client_secret and user_id to the grant. Retrieve the client from DB to validate the secret. Retrieve the client from DB to issue the token.

Create a client using passport:client --personal for each user provider. Issue access token using $user->createToken(). Pass provider and user_id to the grant. Retrieve the client from DB for the given provider to issue the token.