Initial work on matrix-homeserver-proxy role and eliminating matrix-nginx-proxy

This is still very far from usable.

Various bridges and bots are still talking to
`matrix-nginx-proxy` instead of the new `matrix-homeserver-proxy` role.
These services need to be reworked. While reworking them,
various cleanups are being done as well as adding Traefik-labels to
those that need them.

roles/custom/matrix-homeserver-proxy/vars/main.yml

@@ -0,0 +1,4 @@
+---
+matrix_homeserver_proxy_client_api_url: "http://{{ matrix_homeserver_proxy_ident }}:8008"
+
+matrix_homeserver_proxy_federation_api_url: "http://{{ matrix_homeserver_proxy_ident }}:8048"