docker (demo): fix starting + better UX:

- Use the new `wait_for_service` option to be sure that Prosody is launched.
- Use the new `init_script_path` option to initiate forums and bookmark a demo room.
- Activate MUC service.
- Change log formats to make them more readable.

docker/backend-dev-demo/Dockerfile

@@ -22,10 +22,11 @@ RUN ./entrypoint.sh \
 RUN ./entrypoint.sh \
     # and a demo account
     libervia-cli profile create demo -j demo@server1.test -p "demo"  && \
-    # we create a bookmark to have something to test in chat
-    libervia-cli bookmarks add -pdemo -a demo@server1.test\
     libervia-backend stop
 
+COPY --chown=libervia:libervia forums.json /home/libervia/
+COPY --chown=libervia:libervia scripts/init_script.sh /home/libervia/
+
 USER libervia
 # HTTP Upload
 EXPOSE 7777