feat(aria/tree): adds rtl keyboard functionality for tree

Updates aria tree keyboard functionality to have RightArrow
collapse and LeftArrow expand for rtl.

Author: essjay05

src/aria/private/tree/tree.ts

@@ -168,6 +168,9 @@ export interface TreeInputs<V> extends Omit<ListInputs<TreeItemPattern<V>, V>, '
 
   /** The aria-current type. */
   currentType: SignalLike<'page' | 'step' | 'location' | 'date' | 'time' | 'true' | 'false'>;
+
+  /** The text direction of the tree. */
+  textDirection: SignalLike<'ltr' | 'rtl'>;
 }
 
 export interface TreePattern<V> extends TreeInputs<V> {}
@@ -205,36 +208,39 @@ export class TreePattern<V> {
   /** Whether the tree selection follows focus. */
   readonly followFocus = computed(() => this.inputs.selectionMode() === 'follow');
 
+  /** Whether the tree direction is RTL. */
+  readonly isRtl = computed(() => this.inputs.textDirection() === 'rtl');
+
   /** The key for navigating to the previous item. */
   readonly prevKey = computed(() => {
     if (this.inputs.orientation() === 'vertical') {
       return 'ArrowUp';
     }
-    return this.inputs.textDirection() === 'rtl' ? 'ArrowRight' : 'ArrowLeft';
+    return this.isRtl() ? 'ArrowRight' : 'ArrowLeft';
   });
 
   /** The key for navigating to the next item. */
   readonly nextKey = computed(() => {
     if (this.inputs.orientation() === 'vertical') {
       return 'ArrowDown';
     }
-    return this.inputs.textDirection() === 'rtl' ? 'ArrowLeft' : 'ArrowRight';
+    return this.isRtl() ? 'ArrowLeft' : 'ArrowRight';
   });
 
   /** The key for collapsing an item or moving to its parent. */
   readonly collapseKey = computed(() => {
     if (this.inputs.orientation() === 'horizontal') {
       return 'ArrowUp';
     }
-    return this.inputs.textDirection() === 'rtl' ? 'ArrowRight' : 'ArrowLeft';
+    return this.isRtl() ? 'ArrowRight' : 'ArrowLeft';
   });
 
   /** The key for expanding an item or moving to its first child. */
   readonly expandKey = computed(() => {
     if (this.inputs.orientation() === 'horizontal') {
       return 'ArrowDown';
     }
-    return this.inputs.textDirection() === 'rtl' ? 'ArrowLeft' : 'ArrowRight';
+    return this.isRtl() ? 'ArrowLeft' : 'ArrowRight';
   });
 
   /** Represents the space key. Does nothing when the user is actively using typeahead. */