Add matrix well-known files for opendev

These let the opendev.org matrix address map to our EMS homeserver.

Change-Id: I35677c1872d52dbcf7c86cec8a6e5eac187bf167

docker/gitea/custom/public/.well-known/matrix/client

@@ -0,0 +1,8 @@
+{
+    "m.homeserver": {
+        "base_url": "https://opendev.ems.host"
+    },
+    "m.identity_server": {
+        "base_url": "https://vector.im"
+    }
+}

docker/gitea/custom/public/.well-known/matrix/server

@@ -0,0 +1,3 @@
+{
+    "m.server": "opendev.ems.host:443"
+}