Feature request: Allow checking of values in JWT against fixed strings

[elgordino]

I would like the ability to check values in the JWT against set values (strings, booleans etc)

For example if the user's token contains 'allow_write:true` I would like to be able to check for this, rather than having to traverse the database to find the users permissions.

This will reduce the DB overhead of the security rules as it would not be necessary to retrieve data from any tables other than the one being updated (providing the user_id is on the table being updated).

There's some more detail on this towards the end of this blog post https://dev.to/lineup-ninja/modelling-teams-and-user-security-with-hasura-204i

This is just a nice to have, particularly for any users migrating from Firebase.