Describe the feature

OAuthlib should try to manage the token_type_hint itself, instead of relying on the application. Every "RFC code" should be in oauthlib and not in the application, which is prone to errors.

Additional context

RFC7008 describe the field as below:

   token_type_hint  OPTIONAL.  A hint about the type of the token
       submitted for revocation.  Clients MAY pass this parameter in
       order to help the authorization server to optimize the token
       lookup.  If the server is unable to locate the token using
       the given hint, it MUST extend its search across all of its
       supported token types.  An authorization server MAY ignore
       this parameter, particularly if it is able to detect the
       token type automatically.

Also, as bonus point, we could handle custom token type, as allowed by the specification.