Chat Federation (and a lot more) WIP:

Note: websocket s2s is not working yet, still WIP.

New Features

* Chat Federation:
  * You can now connect to a remote chat with your local account.
  * This remote connection is done using a custom implementation of [XEP-0468: WebSocket S2S](https://xmpp.org/extensions/xep-0468.html), using some specific discovering method (so that it will work without any DNS configuration).

Minor changes and fixes

* Possibility to debug Prosody in development environments.
* Using process.spawn instead of process.exec to launch Prosody (safer, and more optimal).
* Prosody AppImage: fix path mapping: we only map necessary /etc/ subdir, so that the AppImage can access to /etc/resolv.conf, /etc/hosts, ...
* Prosody AppImage: hidden debug mode to disable lua-unbound, that seems broken in some docker dev environments.

server/lib/uri/webchat.ts

@@ -11,3 +11,9 @@ export function getWSUri (options: RegisterServerOptions): string | undefined {
   if (base === undefined) { return undefined }
   return base + 'xmpp-websocket'
 }
+
+export function getWSS2SUri (options: RegisterServerOptions): string | undefined {
+  const base = getBaseWebSocketRoute(options) // can be undefined if Peertube is too old
+  if (base === undefined) { return undefined }
+  return base + 'xmpp-websocket-s2s'
+}