Implement word-wise mouse selection

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/gpui/src/app.rs

@@ -3651,6 +3651,7 @@ mod tests {
             Event::LeftMouseDown {
                 position: Default::default(),
                 cmd: false,
+                click_count: 1,
             },
             cx,
         );

crates/gpui/src/platform/event.rs

@@ -15,7 +15,7 @@ pub enum Event {
     LeftMouseDown {
         position: Vector2F,
         cmd: bool,
-        count: usize,
+        click_count: usize,
     },
     LeftMouseUp {
         position: Vector2F,

crates/gpui/src/platform/mac/event.rs

@@ -94,7 +94,7 @@ impl Event {
                     cmd: native_event
                         .modifierFlags()
                         .contains(NSEventModifierFlags::NSCommandKeyMask),
-                    count: native_event.clickCount() as usize,
+                    click_count: native_event.clickCount() as usize,
                 })
             }
             NSEventType::NSLeftMouseUp => window_height.map(|window_height| Self::LeftMouseUp {