* fix validation and don't use built-in validation UI

Co-authored-by: Bruno Windels <brunow@element.io>

config: Add detail to auto_join_rooms comment

Signed-off-by: Gary Dykstra <gary@dykstranet.com>

Also add a few more IP ranges to the default blacklist.

This could arguably replace the existing admin API for `/members`, however that is out of scope of this change.

This sort of endpoint is ideal for moderation use cases as well as other applications, such as needing to retrieve various bits of information about a room to perform a task (like syncing power levels between two places). This endpoint exposes nothing more than an admin would be able to access with a `select *` query on their database.

fixes #9171

* Fixes a case where no summary text was returned.
* The use of messages_from_person vs. messages_from_person_and_others
  was tweaked to depend on whether there was 1 sender or multiple senders,
  not based on if there was 1 room or multiple rooms.

Signed-off-by: Jan Christian Grünhage <jan.christian@gruenhage.xyz>

Context, Fixes: https://github.com/matrix-org/synapse/issues/9263

In the past to fix an issue with old Riots re-requesting threepid validation tokens, we raised a `LoginError` during UIA instead of `InteractiveAuthIncompleteError`. This is now breaking the way Tchap logs in - which isn't standard, but also isn't disallowed by the spec.

An easy fix is just to remove the 4 year old workaround.

There's some prelimiary work here to pull out the construction of a jinja environment to a separate function.

I wanted to load the template at display time rather than load time, so that it's easy to update on the fly. Honestly, I think we should do this with all our templates: the risk of ending up with malformed templates is far outweighed by the improved turnaround time for an admin trying to update them.

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

There are going to be a couple of paths to get to the final step of SSO reg, and I want the URL in the browser to consistent. So, let's move the final step onto a separate path, which we redirect to.

* synapse.app.base: only call gc.freeze() on CPython

gc.freeze() is an implementation detail of CPython garbage collector,
and notably does not exist on PyPy.

Rather than playing whack-a-mole and skipping the call when under PyPy,
simply restrict it to CPython because the whole gc module is
implementation-defined.

Signed-off-by: Ivan Shapovalov <intelfx@intelfx.name>

Adds note about updating dh-virtualenv once we drop support for Xenial.

We can't update now, because it needs debhelper 12, while Xenial only
backports 10.

Signed-off-by: Dan Callahan <danc@element.io>