feat(wm): add new cmd to set active border offset

This commit introduces a new command, active-window-border-offset, which
allows the user to offset the starting position of the active window
border, thereby allowing for thicker or thinner active window borders,
when used in conjunction with the active-window-border-width command.

resolve #232

komorebi-core/src/lib.rs

@@ -107,6 +107,7 @@ pub enum SocketMessage {
     ActiveWindowBorder(bool),
     ActiveWindowBorderColour(WindowKind, u32, u32, u32),
     ActiveWindowBorderWidth(i32),
+    ActiveWindowBorderOffset(i32),
     InvisibleBorders(Rect),
     WorkAreaOffset(Rect),
     MonitorWorkAreaOffset(usize, Rect),