Allow for the creation of a support user.
A support user can access the server, join rooms, interact with other users, but does not appear in the user directory nor does it contribute to monthly active user limits.
We might as well treat all refresh_tokens as invalid. Just return a 403 from
/tokenrefresh, so that we don't have a load of dead, untestable code hanging
around.
Still TODO: removing the table from the schema.
Add a 'devices' table to the storage, as well as a 'device_id' column to
refresh_tokens.
Allow the client to pass a device_id, and initial_device_display_name, to
/login. If login is successful, then register the device in the devices table
if it wasn't known already. If no device_id was supplied, make one up.
Associate the device_id with the access token and refresh token, so that we can
get at it again later. Ensure that the device_id is copied from the refresh
token to the access_token when the token is refreshed.
Removes device_id and ClientInfo
device_id is never actually written, and the matrix.org DB has no
non-null entries for it. Right now, it's just cluttering up code.
This doesn't remove the columns from the database, because that's
fiddly.
This allows refresh tokens to be exchanged for (access_token,
refresh_token).
It also starts issuing them on login, though no clients currently
interpret them.
