Use WlOutput instead of output names for matching

With a shared wayland connection between the code here and iced, if we
don't bind outputs outselves, we can have `WlOutput`s that match.

This simplifies things.

src/wayland/capture.rs

@@ -41,7 +41,7 @@ impl std::hash::Hash for CaptureSource {
 #[derive(Clone, Debug, Default)]
 pub struct CaptureFilter {
     // TODO: Use `WlOutput` when one Wayland connection is used
-    pub workspaces_on_outputs: Vec<String>,
+    pub workspaces_on_outputs: Vec<wl_output::WlOutput>,
     pub toplevels_on_workspaces: Vec<zcosmic_workspace_handle_v1::ZcosmicWorkspaceHandleV1>,
 }