Add UI/UX for moving channels (#2976)

TODO:

- [x] Add drag and drop
- [x] Polish up in-flight decisions.
- [x] Fix chat panel panic
- [x] Add nice hover effect highlighting the matching ones
- [x] Fix and test keyboard

Release Notes:

- N/A

crates/workspace/src/pane.rs

@@ -1383,7 +1383,7 @@ impl Pane {
                         let theme = theme::current(cx).clone();
 
                         let detail = detail.clone();
-                        move |dragged_item: &DraggedItem, cx: &mut ViewContext<Workspace>| {
+                        move |_, dragged_item: &DraggedItem, cx: &mut ViewContext<Workspace>| {
                             let tab_style = &theme.workspace.tab_bar.dragged_tab;
                             Self::render_dragged_tab(
                                 &dragged_item.handle,

crates/workspace/src/workspace.rs

@@ -33,8 +33,8 @@ use gpui::{
     },
     impl_actions,
     platform::{
-        CursorStyle, MouseButton, PathPromptOptions, Platform, PromptLevel, WindowBounds,
-        WindowOptions,
+        CursorStyle, ModifiersChangedEvent, MouseButton, PathPromptOptions, Platform, PromptLevel,
+        WindowBounds, WindowOptions,
     },
     AnyModelHandle, AnyViewHandle, AnyWeakViewHandle, AppContext, AsyncAppContext, Entity,
     ModelContext, ModelHandle, SizeConstraint, Subscription, Task, View, ViewContext, ViewHandle,
@@ -3815,6 +3815,10 @@ impl View for Workspace {
             cx.focus(&self.active_pane);
         }
     }
+
+    fn modifiers_changed(&mut self, e: &ModifiersChangedEvent, cx: &mut ViewContext<Self>) -> bool {
+        DragAndDrop::<Workspace>::update_modifiers(e.modifiers, cx)
+    }
 }
 
 impl ViewId {