feat(wm): add command to create new workspace

This commit adds a new command, 'komorebic.exe new-workspace', which
will append a new, empty workspace, to the list of workspaces on the
currently focused monitor, and then switch focus to it.

Also took the opportunity to clean up some unnecessary unwraps in
komorebic/src/main.rs.

resolve #4

komorebi-core/src/lib.rs

@@ -39,6 +39,7 @@ pub enum SocketMessage {
     FlipLayout(LayoutFlip),
     // Monitor and Workspace Commands
     EnsureWorkspaces(usize, usize),
+    NewWorkspace,
     Stop,
     TogglePause,
     Retile,