Fixes#8966.
* Factor out build_synapse_client_resource_tree
Start a function which will mount resources common to all workers.
* Move sso init into build_synapse_client_resource_tree
... so that we don't have to do it for each worker
* Fix SSO-login-via-a-worker
Expose the SSO login endpoints on workers, like the documentation says.
* Update workers config for new endpoints
Add documentation for endpoints recently added (#8942, #9017, #9262)
* remove submit_token from workers endpoints list
this *doesn't* work on workers (yet).
* changelog
* Add a comment about the odd path for SAML2Resource
