Remove legacy code related to deprecated `trust_identity_server_for_password_resets` config flag (#11333)

* remove code legacy code related to deprecated config flag "trust_identity_server_for_password_resets" from synapse/config/emailconfig.py

* remove legacy code supporting depreciated config flag "trust_identity_server_for_password_resets" from synapse/config/registration.py

* remove legacy code supporting depreciated config flag "trust_identity_server_for_password_resets" from synapse/handlers/identity.py

* add tests to ensure config error is thrown and synapse refuses to start when depreciated config flag is found

* add changelog

* slightly change behavior to only check for deprecated flag if set to 'true'

* Update changelog.d/11333.misc

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: reivilibre <oliverw@matrix.org>

`synapse.config.__main__` has the possibility to read a config item. This can be used to conveniently also validate the config is valid before trying to start Synapse.

 The "read" command broke in https://github.com/matrix-org/synapse/pull/10916

 as it now requires passing in "server.server_name" for example.

 Also made the read command optional so one can just call this with just the confirm file reference and get a "Config parses OK" if things are ok.

Signed-off-by: Jason Robinson <jasonr@matrix.org>
Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

This reverts #11019 and structures the code a bit more like it was before #10985.

The global cache state must be reset before running the tests since other test
cases might have configured caching (and thus touched the global state).

Hopefully this fixes these tests sometimes failing in CI.

This removes the magic allowing accessing configurable
variables directly from the config object. It is now required
that a specific configuration class is used (e.g. `config.foo`
must be replaced with `config.server.foo`).

Allow using several directories in read_templates.

Fixes #9778

ACME v1 has been fully decommissioned for existing installs on June 1st 2021(see https://community.letsencrypt.org/t/end-of-life-plan-for-acmev1/88430/27), so we can now safely remove it from Synapse.

we don't need to reload the tls cert if we don't have any tls listeners.

Follow-up to #9280.

Part of #9744

Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.

`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl&gt;`>

 - Update black version to the latest
 - Run black auto formatting over the codebase
    - Run autoformatting according to [`docs/code_style.md
`](https://github.com/matrix-org/synapse/blob/80d6dc9783aa80886a133756028984dbf8920168/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version

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

Fixes https://github.com/matrix-org/synapse/issues/6583

This mostly applise to `*stateGroupCache*` and co.

Broke in #6391.

This is already correctly done when we instansiate the cache, but wasn't
when it got reloaded (which always happens at least once on startup).

This is a cherry-pick of 1a1da60a (#7470)
to the release-v1.13.0 branch.

Attempts to clarify the sample config for databases, and add some stuff about
tcp keepalives to `postgres.md`.

Extends #5794 etc to the SimpleHttpClient so that it also applies to non-federation requests.

Fixes #7092.

Ensure good comprehension hygiene using flake8-comprehensions.

Template config files

* Imagine a system composed entirely of x, y, z etc and the basic operations..

Wait George, why XOR? Why not just neq?

George: Eh, I didn't think of that..

Co-Authored-By: Erik Johnston <erik@matrix.org>

- Put the default window_size back to 1000ms (broken by #5181)
- Make the `rc_federation` config actually do something
- fix an off-by-one error in the 'concurrent' limit
- Avoid creating an unused `_PerHostRatelimiter` object for every single
  incoming request

* Pull config_dir_path and data_dir_path calculation out of read_config_files

* Pass config_dir_path and data_dir_path into read_config

test threepid checking

This allows specifying who and what is allowed to be published onto the
public room list