Move accessibility setup to accessibility module (#12784)

# Objective

- Reduce the size of `create_windows` and isolate accessibility setup
logic.

## Solution

- Move accessibility setup for new windows to the `accessibility`
module.

## Comments

This is a small refactor, no behavior changes.

crates/bevy_winit/src/accessibility.rs

@@ -8,7 +8,7 @@ use std::{
 use accesskit_winit::Adapter;
 use bevy_a11y::{
     accesskit::{
-        ActionHandler, ActionRequest, NodeBuilder, NodeClassSet, NodeId, Role, TreeUpdate,
+        ActionHandler, ActionRequest, NodeBuilder, NodeClassSet, NodeId, Role, Tree, TreeUpdate,
     },
     AccessibilityNode, AccessibilityRequested, AccessibilitySystem, Focus,
 };
@@ -44,6 +44,37 @@ impl ActionHandler for WinitActionHandler {
     }
 }
 
+/// Prepares accessibility for a winit window.
+pub(crate) fn prepare_accessibility_for_window(
+    winit_window: &winit::window::Window,
+    entity: Entity,
+    name: String,
+    accessibility_requested: AccessibilityRequested,
+    adapters: &mut AccessKitAdapters,
+    handlers: &mut WinitActionHandlers,
+) {
+    let mut root_builder = NodeBuilder::new(Role::Window);
+    root_builder.set_name(name.into_boxed_str());
+    let root = root_builder.build(&mut NodeClassSet::lock_global());
+
+    let accesskit_window_id = NodeId(entity.to_bits());
+    let handler = WinitActionHandler::default();
+    let adapter = Adapter::with_action_handler(
+        winit_window,
+        move || {
+            accessibility_requested.set(true);
+            TreeUpdate {
+                nodes: vec![(accesskit_window_id, root)],
+                tree: Some(Tree::new(accesskit_window_id)),
+                focus: accesskit_window_id,
+            }
+        },
+        Box::new(handler.clone()),
+    );
+    adapters.insert(entity, adapter);
+    handlers.insert(entity, handler);
+}
+
 fn window_closed(
     mut adapters: NonSendMut<AccessKitAdapters>,
     mut receivers: ResMut<WinitActionHandlers>,

crates/bevy_winit/src/winit_windows.rs

@@ -1,8 +1,4 @@
-use accesskit_winit::Adapter;
-use bevy_a11y::{
-    accesskit::{NodeBuilder, NodeClassSet, NodeId, Role, Tree, TreeUpdate},
-    AccessibilityRequested,
-};
+use bevy_a11y::AccessibilityRequested;
 use bevy_ecs::entity::Entity;
 
 use bevy_ecs::entity::EntityHashMap;
@@ -15,7 +11,7 @@ use winit::{
 };
 
 use crate::{
-    accessibility::{AccessKitAdapters, WinitActionHandler, WinitActionHandlers},
+    accessibility::{prepare_accessibility_for_window, AccessKitAdapters, WinitActionHandlers},
     converters::{convert_enabled_buttons, convert_window_level, convert_window_theme},
 };
 
@@ -212,28 +208,14 @@ impl WinitWindows {
 
         let winit_window = winit_window_builder.build(event_loop).unwrap();
         let name = window.title.clone();
-
-        let mut root_builder = NodeBuilder::new(Role::Window);
-        root_builder.set_name(name.into_boxed_str());
-        let root = root_builder.build(&mut NodeClassSet::lock_global());
-
-        let accesskit_window_id = NodeId(entity.to_bits());
-        let handler = WinitActionHandler::default();
-        let accessibility_requested = accessibility_requested.clone();
-        let adapter = Adapter::with_action_handler(
+        prepare_accessibility_for_window(
             &winit_window,
-            move || {
-                accessibility_requested.set(true);
-                TreeUpdate {
-                    nodes: vec![(accesskit_window_id, root)],
-                    tree: Some(Tree::new(accesskit_window_id)),
-                    focus: accesskit_window_id,
-                }
-            },
-            Box::new(handler.clone()),
+            entity,
+            name,
+            accessibility_requested.clone(),
+            adapters,
+            handlers,
         );
-        adapters.insert(entity, adapter);
-        handlers.insert(entity, handler);
 
         // Do not set the grab mode on window creation if it's none. It can fail on mobile.
         if window.cursor.grab_mode != CursorGrabMode::None {