New option to use and configure Prosody mod_firewall WIP (#97):

* new setting
* new configuration screen for Peertube admins
* include the mod_firewall module
* load mod_firewall if enabled
* sys admin can disable the firewall config editing by creating a
  special file on the disk
* user documentation

assets/styles/style.scss

@@ -9,4 +9,5 @@
 @use "elements/index";
 @use "video";
 @use "configuration/configuration";
+@use "admin/firewall/firewall";
 @use "list-rooms/list-rooms.scss";