Initial pass at DDNS support for client addresses

This is a first pass attempt at adding support for using ddns (really any resolvable domain name) as the address in access list clients.

This helps make it possible to restrict access to hosts using a dynamic public IP (e.g. allow access to a proxied host from your local network only via ddns address).

Current approach is hacky since it was developed by manually replacing files in an existing npm docker container. Future commits will integrate this better and avoid needing to patch/intercept existing APIs.

See associated PR for more details.

backend/schema/endpoints/access-lists.json

@@ -36,6 +36,10 @@
 				{
 					"type": "string",
 					"pattern": "^all$"
+				},
+				{
+					"type": "string",
+					"pattern": "^ddns:[\\w\\.]+$"
 				}
 			]
 		},