Fixes https://github.com/matrix-org/synapse/issues/5861

Adds support for the v2 lookup API as defined in [MSC2134](https://github.com/matrix-org/matrix-doc/pull/2134). Currently this is only used for 3PID invites.

Sytest PR: https://github.com/matrix-org/sytest/pull/679

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>

Some of the caches on worker processes were not being correctly invalidated
when a room's state was changed in a way that did not affect the membership
list of the room.

We need to make sure we send out cache invalidations even when no memberships
are changing.

Add GET method to admin API /users/@user:dom/admin

MSC2197 Search Filters over Federation

Refactor MatrixFederationAgent to retry SRV.

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

* Allow schema deltas to be engine-specific

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

* Newsfile

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

* Code style (Black)

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Increase profile display name limit

Add config option to sign remote key query responses with a separate key.

public_base_url is actually public_baseurl

Admin API: Set adminship of a user

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Signed-off-by: Aaron Raimist <aaron@raim.ist>

Propagate opentracing contexts through EDUs
Co-Authored-By: Richard van der Hoff <1389908+richvdh@users.noreply.github.com>

Remove shared secret registration

Propagate opentracing contexts across workers


Also includes some Convenience modifications to opentracing for servlets, notably:
- Add boolean to skip the whitelisting check on inject
  extract methods. - useful when injecting into carriers
  locally. Otherwise we'd always have to include our
  own servername and whitelist our servername
- start_active_span_from_request instead of header
- Add boolean to decide whether to extract context
  from a request to a servlet

This type of registration was probably never used. It only includes the
user name in the HMAC but not the password.

Shared secret registration is still available via
client/r0/admin/register.

Signed-off-by: Manuel Stahl <manuel.stahl@awesome-technologies.de>

This reverts commit 27a686e5.

This reverts commit 3320aaab.

Retry well known on fail

Add opentracing tags and logs for e2e keys