feat(wm): restrict border window to outline

This commit moves the border window drawing logic into the WNDPROC
callback and uses BeginPaint -> Rectangle -> Endpaint to draw a
rectangle around the outside of the window in a specific colour that is
not black, which is used as the transparency colour with
SetLayeredWindowAttributes.

All of this results in a non-filled border rect and a much nicer
experience for users who are using transparency or translucent effects
on their windows.

This commit also introduces an optional second active border colour when
the user is focused on a stack of windows. If this is not set, the
default colour for single windows will be used.

Finally, a bunch of small issues relating to the border window staying
drawn on the screen even when there are no active windows on a workspace
have been addressed.

resolve #201

komorebi-core/src/lib.rs

@@ -98,7 +98,7 @@ pub enum SocketMessage {
     WatchConfiguration(bool),
     CompleteConfiguration,
     ActiveWindowBorder(bool),
-    ActiveWindowBorderColour(u32, u32, u32),
+    ActiveWindowBorderColour(WindowKind, u32, u32, u32),
     InvisibleBorders(Rect),
     WorkAreaOffset(Rect),
     ResizeDelta(i32),
@@ -134,6 +134,13 @@ impl FromStr for SocketMessage {
     }
 }
 
+#[derive(Copy, Clone, Debug, Serialize, Deserialize, Display, EnumString, ArgEnum, JsonSchema)]
+#[strum(serialize_all = "snake_case")]
+pub enum WindowKind {
+    Single,
+    Stack,
+}
+
 #[derive(Copy, Clone, Debug, Serialize, Deserialize, Display, EnumString, ArgEnum, JsonSchema)]
 #[strum(serialize_all = "snake_case")]
 pub enum StateQuery {