Multi-personality polylith binary (#1552)

* Initial work oon multipersonality binary

* Remove old binaries

* Monolith and polylith binaries

* Better logging

* dendrite-poly-multi

* Fix path

* Copyright notices etc

* Tweaks

* Update Docker, INSTALL.md

* Take first argument if flags package doesn't find any args

* Postgres 9.6 or later, fix some more Docker stuff

* Don't create unnecessary e2ekey DB

* Run go mod tidy

build/docker/docker-compose.monolith.yml

@@ -4,7 +4,6 @@ services:
     hostname: monolith
     image: matrixdotorg/dendrite-monolith:latest
     command: [
-      "--config=dendrite.yaml",
       "--tls-cert=server.crt",
       "--tls-key=server.key"
     ]