OAuth2Server model access_token field too small

The Microsoft Graph API accepts an access token for authorization. The access token may be acquired using the client credentials grant type with a client ID and secret from the https://login.microsoftonline.com/<tenant ID>/oauth2/v2.0/token endpoint.

The access token returned has, roughly, 1600 characters. Note that it is a proper JWT.

The current schema for the cm_oauth2_servers table limits the access_token field to 160 characters, probably assuming a generic opaque string for the token instead of a JWT.