Update links to iOS embedder docs to point to new Doxygen docs (#134246)

## Description

Now that we are using Doxygen for building docs for the embedders, this updates the links to point to the correct URLs.

## Related Issues
 - https://github.com/flutter/flutter/issues/124833

## Related PRs
 - https://github.com/flutter/engine/pull/45561

packages/flutter/lib/src/rendering/layer.dart

@@ -919,9 +919,9 @@ class PictureLayer extends Layer {
 ///
 /// See also:
 ///
-///  * <https://api.flutter.dev/javadoc/io/flutter/view/TextureRegistry.html>
+///  * [TextureRegistry](/javadoc/io/flutter/view/TextureRegistry.html)
 ///    for how to create and manage backend textures on Android.
-///  * <https://api.flutter.dev/objcdoc/Protocols/FlutterTextureRegistry.html>
+///  * [TextureRegistry Protocol](/ios-embedder/protocol_flutter_texture_registry-p.html)
 ///    for how to create and manage backend textures on iOS.
 class TextureLayer extends Layer {
   /// Creates a texture layer bounded by [rect] and with backend texture

packages/flutter/lib/src/rendering/texture.dart

@@ -29,9 +29,9 @@ import 'object.dart';
 ///
 /// See also:
 ///
-///  * <https://api.flutter.dev/javadoc/io/flutter/view/TextureRegistry.html>
+///  * [TextureRegistry](/javadoc/io/flutter/view/TextureRegistry.html)
 ///    for how to create and manage backend textures on Android.
-///  * <https://api.flutter.dev/objcdoc/Protocols/FlutterTextureRegistry.html>
+///  * [TextureRegistry Protocol](/ios-embedder/protocol_flutter_texture_registry-p.html)
 ///    for how to create and manage backend textures on iOS.
 class TextureBox extends RenderBox {
   /// Creates a box backed by the texture identified by [textureId], and use

packages/flutter/lib/src/services/restoration.dart

@@ -92,7 +92,7 @@ typedef _BucketVisitor = void Function(RestorationBucket bucket);
 /// ## State Restoration on iOS
 ///
 /// To enable state restoration on iOS, a restoration identifier has to be
-/// assigned to the [FlutterViewController](https://api.flutter.dev/objcdoc/Classes/FlutterViewController.html).
+/// assigned to the [FlutterViewController](/ios-embedder/interface_flutter_view_controller.html).
 /// If the standard embedding (produced by `flutter create`) is used, this can
 /// be accomplished with the following steps:
 ///

packages/flutter/lib/src/widgets/platform_view.dart

@@ -230,13 +230,13 @@ abstract class _DarwinView extends StatefulWidget {
   /// {@macro flutter.widgets.AndroidView.layoutDirection}
   final TextDirection? layoutDirection;
 
-  /// Passed as the `arguments` argument of [-\[FlutterPlatformViewFactory createWithFrame:viewIdentifier:arguments:\]](/objcdoc/Protocols/FlutterPlatformViewFactory.html#/c:objc(pl)FlutterPlatformViewFactory(im)createWithFrame:viewIdentifier:arguments:)
+  /// Passed as the `arguments` argument of [-\[FlutterPlatformViewFactory createWithFrame:viewIdentifier:arguments:\]](/ios-embedder/protocol_flutter_platform_view_factory-p.html#a4e3c4390cd6ebd982390635e9bca4edc)
   ///
   /// This can be used by plugins to pass constructor parameters to the embedded iOS view.
   final dynamic creationParams;
 
   /// The codec used to encode `creationParams` before sending it to the
-  /// platform side. It should match the codec returned by [-\[FlutterPlatformViewFactory createArgsCodec:\]](/objcdoc/Protocols/FlutterPlatformViewFactory.html#/c:objc(pl)FlutterPlatformViewFactory(im)createArgsCodec)
+  /// platform side. It should match the codec returned by [-\[FlutterPlatformViewFactory createArgsCodec:\]](/ios-embedder/protocol_flutter_platform_view_factory-p.html#a32c3c067cb45a83dfa720c74a0d5c93c)
   ///
   /// This is typically one of: [StandardMessageCodec], [JSONMessageCodec], [StringCodec], or [BinaryCodec].
   ///

packages/flutter/lib/src/widgets/texture.dart

@@ -28,9 +28,9 @@ import 'framework.dart';
 ///
 /// See also:
 ///
-///  * <https://api.flutter.dev/javadoc/io/flutter/view/TextureRegistry.html>
+///  * [TextureRegistry](/javadoc/io/flutter/view/TextureRegistry.html)
 ///    for how to create and manage backend textures on Android.
-///  * <https://api.flutter.dev/objcdoc/Protocols/FlutterTextureRegistry.html>
+///  * [TextureRegistry Protocol](/ios-embedder/protocol_flutter_texture_registry-p.html)
 ///    for how to create and manage backend textures on iOS.
 class Texture extends LeafRenderObjectWidget {
   /// Creates a widget backed by the texture identified by [textureId], and use