Fix SemanticsAction naming consistency (#32411)

Removes the `Index` suffix from kMoveCursorForwardByWord and
kMoveCursorBackwardByWord values in the SemanticsAction enum. These were
erroneously copied as-is from the private class members in the dart:ui
implementation in lib/ui/semantics/semantics.dart where the class
members refer to the enum index here. This removes the trailing `Index`
for consistency with the other enum members here.

This is also useful in the context of automated testing for API
consistency between these enums, the ones in dart:ui (native and web
implementations) and the embedder API.

Issue: https://github.com/flutter/flutter/issues/101217

lib/ui/semantics/semantics_node.h

diff --git a/lib/ui/semantics/semantics_node.h b/lib/ui/semantics/semantics_node.h
index 6fc4d73..70c0fcf 100644
--- a/lib/ui/semantics/semantics_node.h
+++ b/lib/ui/semantics/semantics_node.h
@@ -39,8 +39,8 @@
   kDidLoseAccessibilityFocus = 1 << 16,
   kCustomAction = 1 << 17,
   kDismiss = 1 << 18,
-  kMoveCursorForwardByWordIndex = 1 << 19,
-  kMoveCursorBackwardByWordIndex = 1 << 20,
+  kMoveCursorForwardByWord = 1 << 19,
+  kMoveCursorBackwardByWord = 1 << 20,
   kSetText = 1 << 21,
 };
 

shell/platform/fuchsia/flutter/accessibility_bridge.cc

diff --git a/shell/platform/fuchsia/flutter/accessibility_bridge.cc b/shell/platform/fuchsia/flutter/accessibility_bridge.cc
index 79c5a7b..309a468 100644
--- a/shell/platform/fuchsia/flutter/accessibility_bridge.cc
+++ b/shell/platform/fuchsia/flutter/accessibility_bridge.cc
@@ -136,15 +136,14 @@
           flutter::SemanticsAction::kMoveCursorBackwardByCharacter)) {
     output += "kMoveCursorBackwardByCharacter|";
   }
-  if (node.HasAction(
-          flutter::SemanticsAction::kMoveCursorBackwardByWordIndex)) {
-    output += "kMoveCursorBackwardByWordIndex|";
+  if (node.HasAction(flutter::SemanticsAction::kMoveCursorBackwardByWord)) {
+    output += "kMoveCursorBackwardByWord|";
   }
   if (node.HasAction(flutter::SemanticsAction::kMoveCursorForwardByCharacter)) {
     output += "kMoveCursorForwardByCharacter|";
   }
-  if (node.HasAction(flutter::SemanticsAction::kMoveCursorForwardByWordIndex)) {
-    output += "kMoveCursorForwardByWordIndex|";
+  if (node.HasAction(flutter::SemanticsAction::kMoveCursorForwardByWord)) {
+    output += "kMoveCursorForwardByWord|";
   }
   if (node.HasAction(flutter::SemanticsAction::kPaste)) {
     output += "kPaste|";