* Rewrites the demo documentation to be clearer, accurate, and moves it to our documentation tree.
* Improvements to the demo scripts:
	* `clean.sh` now runs `stop.sh` first to avoid zombie processes.
	* Uses more modern Synapse configuration (and removes some obsolete configuration).
	* Consistently use the HTTP ports for server name, etc.
	* Remove the `demo/etc` directory and place everything into the `demo/808x` directories.

* Rename scripts-dev to have suffices

* Update references to `scripts-dev`

* Changelog

* These scripts don't pass mypy

* Two scripts are basically entry_points already
* Move and rename scripts/* to synapse/_scripts/*.py
* Delete sync_room_to_group.pl
* Expose entry points in setup.py
* Update linter script and config
* Fixup scripts & docs mentioning scripts that moved

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

...and various code supporting it.

The /spaces endpoint was from an old version of MSC2946 and included
both a Client-Server and Server-Server API. Note that the unstable
/hierarchy endpoint (from the final version of MSC2946) is not yet
removed.

And clean-up the endpoints which should be routed to workers.

The presence of this method was confusing, and mostly present for backwards
compatibility. Let's get rid of it.

Part of #11733

Since it is reasonable to give a future or past auth provider,
which might not be in the current configuration.

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

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

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

The StreamHandler takes a stream parameter, not location.

Part of the Tchap Synapse mainlining.

This allows modules to implement extra logic to figure out whether a given 3PID can be added to the local homeserver. In the Tchap use case, this will allow a Synapse module to interface with the custom endpoint /internal_info.

This document isn't really relevant any more, and its existence is more confusing than helpful.

Also remove support for non-HTTP(S) web_client_location.

Co-authored-by: reivilibre <olivier@librepush.net>

Co-authored-by: reivilibre <olivier@librepush.net>

Only allow files which file size and content types match configured
limits to be set as avatar.

Most of the inspiration from the non-test code comes from matrix-org/synapse-dinsic#19

This is in the context of mainlining the Tchap fork of Synapse. Currently in Tchap usernames are derived from the user's email address (extracted from the UIA results, more specifically the m.login.email.identity step).
This change also exports the check_username method from the registration handler as part of the module API, so that a module can check if the username it's trying to generate is correct and doesn't conflict with an existing one, and fallback gracefully if not.

Co-authored-by: David Robertson <davidr@element.io>

This is mostly motivated by the tchap use case, where usernames are automatically generated from the user's email address (in a way that allows figuring out the email address from the username). Therefore, it's an issue if we respond to requests on /register and /register/available with M_USER_IN_USE, because it can potentially leak email addresses (which include the user's real name and place of work).

This commit adds a flag to inhibit the M_USER_IN_USE errors that are raised both by /register/available, and when providing a username early into the registration process. This error will still be raised if the user completes the registration process but the username conflicts. This is particularly useful when using modules (https://github.com/matrix-org/synapse/pull/11790 adds a module callback to set the username of users at registration) or SSO, since they can ensure the username is unique.

More context is available in the PR that introduced this behaviour to synapse-dinsic: matrix-org/synapse-dinsic#48 - as well as the issue in the matrix-dinsic repo: matrix-org/matrix-dinsic#476

* Make functions in python deltas optional

It's annoying to always have to write stubs for these.

* Documentation for delta files

* changelog