Port receipt and read markers to async/wait

Port replication http server endpoints to async/await

Port room rest handlers to async/await

Port federation_server to async/await

Merge branch 'erikj/federation_server_async_await' of github.com:matrix-org/synapse into erikj/receipts_async_await

* Don't use a virtualenv

* Generate the server's signing key to allow it to start

* Add signing key paths to CI configuration files

* Use a Python script to create the postgresql database

* Improve logging

another typo

fix typo

Quick fix to ensure cache descriptors always return deferreds

Make room directory search case insensitive

This adds:

* a test sqlite database
* a configuration file for the sqlite database
* a configuration file for a postgresql database (using the credentials in `.buildkite/docker-compose.pyXX.pgXX.yaml`)

as well as a new script named `.buildkite/scripts/test_synapse_port_db.sh` that:

1. installs Synapse
2. updates the test sqlite database to the latest schema and runs background updates on it
3. creates an empty postgresql database
4. run the `synapse_port_db` script to migrate the test sqlite database to the empty postgresql database (with coverage)

Step `2` is done via a new script located at `scripts-dev/update_database`.

The test sqlite database is extracted from a SyTest run, so that it can be considered as an actual homeserver's database with actual data in it.

Signed-off-by: Tobia De Koninck <LEDfan@users.noreply.github.com>