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>

Synapse 1.5.0rc2 (2019-10-28)
=============================

Bugfixes
--------

- Update list of boolean columns in `synapse_port_db`. ([\#6247](https://github.com/matrix-org/synapse/issues/6247))
- Fix /keys/query API on workers. ([\#6256](https://github.com/matrix-org/synapse/issues/6256))
- Improve signature checking on some federation APIs. ([\#6262](https://github.com/matrix-org/synapse/issues/6262))

Internal Changes
----------------

- Move schema delta files to the correct data store. ([\#6248](https://github.com/matrix-org/synapse/issues/6248))
- Small performance improvement by removing repeated config lookups in room stats calculation. ([\#6255](https://github.com/matrix-org/synapse/issues/6255))

Make sure that we check that events sent over /send_join, /send_leave, and
/invite, are correctly signed and come from the expected servers.

* make EventContext use an attr

delete keys when deleting backup versions

Remove repeated calls to config.stats_enabled.

Fix /keys/query API on workers.

The necessary getters were added only to the master store and not the
worker stores.

Turns out that fetching variables from the config object is expensive,
so doing it once at startup avoids unnecessary work.

Reduce debug logging overhead

Make user stats less verbose

Using % will cause the string to be generated even if debugging
is off.

This avoids calculating __repr__ unless we are going to log.

I believe that string formatting ~10-15 sized events will
take a proportion of CPU time.

Move schema delta files to the correct data store.

Add new boolean column to synapse_port_db