We then use this in both login and authhandler, the latter being where we process m.login.password
User Interactive Authentication responses, which can now include identifiers

…ing tests

Co-authored-by: Patrick Cloke <clokep@users.noreply.github.com>

…r_param_ui_auth

* 'develop' of github.com:matrix-org/synapse: (369 commits)
  Add functions to `MultiWriterIdGen` used by events stream (#8164)
  Do not allow send_nonmember_event to be called with shadow-banned users. (#8158)
  Changelog fixes
  1.19.1rc1
  Make StreamIdGen `get_next` and `get_next_mult` async  (#8161)
  Wording fixes to 'name' user admin api filter (#8163)
  Fix missing double-backtick in RST document
  Search in columns 'name' and 'displayname' in the admin users endpoint (#7377)
  Add type hints for state. (#8140)
  Stop shadow-banned users from sending non-member events. (#8142)
  Allow capping a room's retention policy (#8104)
  Add healthcheck for default localhost 8008 port on /health endpoint. (#8147)
  Fix flaky shadow-ban tests. (#8152)
  Fix join ratelimiter breaking profile updates and idempotency (#8153)
  Do not apply ratelimiting on joins to appservices (#8139)
  Don't fail /submit_token requests on incorrect session ID if request_token_inhibit_3pid_errors is turned on (#7991)
  Do not apply ratelimiting on joins to appservices (#8139)
  Micro-optimisations to get_auth_chain_ids (#8132)
  Allow denying or shadow banning registrations via the spam checker (#8034)
  Stop shadow-banned users from sending invites. (#8095)
  ...