Add read-only home directory support

Only necessary until Electron 14 brings the desktop-portal support for
handling files.

Fixes #20
Fixes #21

org.jitsi.jitsi-meet.yaml

@@ -16,6 +16,9 @@ finish-args:
   - --filesystem=xdg-run/pipewire-0
   - --talk-name=org.freedesktop.Notifications
 
+    # Until Electron 14 with the desktop-portal support
+  - --filesystem=home:ro
+
     # From Chromium source-code for screen-saver inhibition
   - --talk-name=org.gnome.SessionManager
   - --talk-name=org.freedesktop.PowerManagement