Use ESC to cancel dragging in Zed (#30318)

Closes https://github.com/zed-industries/zed/issues/11887

ESC is always captured in terminal due to 


https://github.com/zed-industries/zed/blob/980bfae331dd5078bbba9fe0f3993d9ad5ca6e29/crates/terminal/src/terminal.rs#L1339-L1353

so this part is not fixed.

Otherwise, all other drags are cancelled when ESC is pressed:


https://github.com/user-attachments/assets/6e70a1e5-c244-420b-9dec-ae2ac2997a59


Release Notes:

- Allowed to use ESC to cancel dragging in Zed

crates/gpui/src/app.rs

@@ -1537,6 +1537,17 @@ impl App {
         self.active_drag.is_some()
     }
 
+    /// Stops active drag and clears any related effects.
+    pub fn stop_active_drag(&mut self, window: &mut Window) -> bool {
+        if self.active_drag.is_some() {
+            self.active_drag = None;
+            window.refresh();
+            true
+        } else {
+            false
+        }
+    }
+
     /// Set the prompt renderer for GPUI. This will replace the default or platform specific
     /// prompts with this custom implementation.
     pub fn set_prompt_builder(