Initial support for workspace pinning and moving

Adds support for cosmic-workspace-v2 pin, unpin, move_after, and
move_before requests.

Both features need some work with workspaces span displays mode, so that
will need more fixes later.

We also want to generate a unique id for pinned workspaces to send in
the ext-workspace-v1 protocol. But that isn't a strict requirement for
anything. So I haven't yet fully implemented that. We'll also want to
persist other things, like workspace naming when that's added.

Overall, though, with separate workspaces per display, this is working
pretty well.

cosmic-comp-config/src/workspace.rs

@@ -2,6 +2,8 @@
 
 use serde::{Deserialize, Serialize};
 
+use crate::output::EdidProduct;
+
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 pub struct WorkspaceConfig {
     pub workspace_mode: WorkspaceMode,
@@ -30,3 +32,16 @@ pub enum WorkspaceLayout {
     Vertical,
     Horizontal,
 }
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct OutputMatch {
+    pub name: String,
+    pub edid: Option<EdidProduct>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PinnedWorkspace {
+    pub output: OutputMatch,
+    pub tiling_enabled: bool,
+    // TODO: name, id
+}