backend: support outputs with arbitrary modes

jay-config/src/_private/ipc.rs

@@ -846,6 +846,9 @@ pub enum ClientMessage<'a> {
         monospace: Option<Vec<&'a str>>,
     },
     OpenControlCenter,
+    ConnectorSupportsArbitraryModes {
+        connector: Connector,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -1096,6 +1099,9 @@ pub enum Response {
     KeymapFromNames {
         keymap: Keymap,
     },
+    ConnectorSupportsArbitraryModes {
+        supports_arbitrary_modes: bool,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]