PointerbuttonState::clear (#21997)

# Objective

To clear the `PointerButtonState`, `clear` is called on each of its
individual fields holding the button state data. Instead add a `clear`
method to `PointerButtonState`.

## Solution

Add a `clear` method to `PointerButtonState` to clear its data.

---------

Co-authored-by: Kevin Chen <chen.kevin.f@gmail.com>

Author: ickshonpe

crates/bevy_picking/src/events.rs

@@ -351,6 +351,15 @@ pub struct PointerButtonState {
     pub dragging_over: HashMap<Entity, HitData>,
 }
 
+impl PointerButtonState {
+    /// Clears all press and drag data tracked for this button on its pointer.
+    pub fn clear(&mut self) {
+        self.pressing.clear();
+        self.dragging.clear();
+        self.dragging_over.clear();
+    }
+}
+
 /// State for all pointers.
 #[derive(Debug, Clone, Default, Resource)]
 pub struct PointerState {
@@ -379,9 +388,7 @@ impl PointerState {
     pub fn clear(&mut self, pointer_id: PointerId) {
         for button in PointerButton::iter() {
             if let Some(state) = self.pointer_buttons.get_mut(&(pointer_id, button)) {
-                state.pressing.clear();
-                state.dragging.clear();
-                state.dragging_over.clear();
+                state.clear();
             }
         }
     }
@@ -699,9 +706,7 @@ pub fn pointer_events(
                 }
 
                 // Finally, we can clear the state of everything relating to presses or drags.
-                state.pressing.clear();
-                state.dragging.clear();
-                state.dragging_over.clear();
+                state.clear();
             }
             // Moved
             PointerAction::Move { delta } => {