cocoa-cb: properly reset window isMoving state on title bar clicks

since the title bar catches the mouse up and down events, the underlying
events view doesn't reset the isMoving state and no mouse movements are
signalled to the core. now we also reset the state in mouse up events
on the title bar.

Fixes #7807

video/out/cocoa-cb/title_bar.swift

@@ -96,6 +96,8 @@ class TitleBar: NSVisualEffectView {
                 window?.zoom(self)
             }
         }
+
+        cocoaCB.window?.isMoving = false
     }
 
     func set(appearance: Any) {