feat(stackbar): make label configurable

This commit introduces a new stackbar label configuration option backed
by the StackbarLabel enum, which now has two variants, Process and
Title.

The state tracker for this option is kept in an AtomicCell, and the
state tracker for StackbarMode has also been changed from an
Arc<Mutex<T>> to an AtomicCell to match.

resolve #826

komorebi-core/src/lib.rs

@@ -142,6 +142,7 @@ pub enum SocketMessage {
     BorderOffset(i32),
     InvisibleBorders(Rect),
     StackbarMode(StackbarMode),
+    StackbarLabel(StackbarLabel),
     StackbarFocusedTextColour(u32, u32, u32),
     StackbarUnfocusedTextColour(u32, u32, u32),
     StackbarBackgroundColour(u32, u32, u32),
@@ -203,6 +204,15 @@ pub enum StackbarMode {
     OnStack,
 }
 
+#[derive(
+    Debug, Copy, Default, Clone, Eq, PartialEq, Display, Serialize, Deserialize, JsonSchema,
+)]
+pub enum StackbarLabel {
+    #[default]
+    Process,
+    Title,
+}
+
 #[derive(
     Default, Copy, Clone, Debug, Eq, PartialEq, Display, Serialize, Deserialize, JsonSchema,
 )]