feat: update build gradle to latest versions

Addresses: https://github.com/rive-app/rive-flutter/issues/398

I also created a fresh plugin using the latest Flutter and copied over the differences.

How to use:
In `android/local.properties` add:
```
rive.ndk.version=25.2.9519653 # set desired version
```

If not specified in a project, it will use the default.

Rive-Android still uses the same ndk version. Should we update that as well?

Diffs=
49bf612fd feat: update build gradle to latest versions (#7475)
a134ab656 Layout joysticks runtime (#7923)
728ac6286 runtime: add tiling to n-slicing (#7934)
e1b4a53ec Revive the WebGL backend (#7948)
813db58e7 Nnnn data binding editor native runtime (#7815)
c71a37173 fix for syntax issue (#7910)
e89437ef6 windows editor: fix format check and use raster ordering disabled (#7937)
7d00d35d3 Fix viewer tess builds (#7935)
455ebad60 Update rive cpp for submodules (#7932)
75e0f9aea runtime: support files with n-slicing defined (#7920)
85b28c39a Update readme of PLS (#7931)
21ecf2775 Fix actions yaml with rive-renderer (#7930)
c33d5d81b Update rive renderer readme (#7929)
b03895fcf Update pls README (#7927)
3316d15ca Refactor pls into runtime (#7914)
b2d27b6bd mark dirty when constraint changes (#7909)
5c14a4a30 Fix Android goldens (#7902)
46a3045ae Improve Vulkan loading and organization (#7873)
160d9eefb Add webp decoder. (#7883)
e992059d6 iOS images unpremult SIMD support (#7875)
ad34dd4da add arithmetic operation and group converters (#7801)
f99c93181 editor: setting up the update callbacks for n-slicing (#7869)
85343a4e1 Fix for bug in Runtime LayoutComponent proxy (#7867)

Co-authored-by: Gordon <pggordonhayes@gmail.com>

.rive_head

@@ -1 +1 @@
-93cc33b45086e528b22d1245a8f7855bac299a21
+49bf612fd8e1e2ec4caecdc45ada328ea5cfbab2

example/android/app/build.gradle

@@ -40,7 +40,7 @@ android {
     defaultConfig {
         // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "com.example.rive_example"
-        minSdkVersion 16
+        minSdkVersion flutter.minSdkVersion
         targetSdkVersion 31
         versionCode flutterVersionCode.toInteger()
         versionName flutterVersionName

example/lib/event_sounds.dart

@@ -1,82 +0,0 @@
-import 'package:flutter/material.dart';
-import 'package:rive/rive.dart';
-import 'package:just_audio/just_audio.dart';
-
-/// An example demonstrating a simple state machine.
-///
-/// The "bumpy" state machine will be activated on tap of the vehicle.
-class EventSounds extends StatefulWidget {
-  const EventSounds({Key? key}) : super(key: key);
-
-  @override
-  State<EventSounds> createState() => _EventSoundsState();
-}
-
-class _EventSoundsState extends State<EventSounds> {
-  final _audioPlayer = AudioPlayer();
-  late final StateMachineController _controller;
-
-  @override
-  void initState() {
-    super.initState();
-    _audioPlayer.setAsset('assets/step.mp3');
-  }
-
-  Future<void> _onRiveInit(Artboard artboard) async {
-    _controller =
-        StateMachineController.fromArtboard(artboard, 'skill-controller')!;
-    artboard.addController(_controller);
-    _controller.addEventListener(onRiveEvent);
-  }
-
-  void onRiveEvent(RiveEvent event) {
-    // Seconds since the event was triggered and it being reported.
-    // This can be used to scrub the audio forward to the precise locaiton
-    // if needed.
-    // ignore: unused_local_variable
-    var seconds = event.secondsDelay;
-
-    if (event.name == 'Step') {
-      _audioPlayer.seek(Duration.zero);
-      _audioPlayer.play();
-    }
-  }
-
-  @override
-  void dispose() {
-    _controller.removeEventListener(onRiveEvent);
-    _controller.dispose();
-    _audioPlayer.dispose();
-    super.dispose();
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    return Scaffold(
-      appBar: AppBar(
-        title: const Text('Event Sounds'),
-      ),
-      body: Stack(
-        children: [
-          Center(
-            child: RiveAnimation.asset(
-              'assets/event_sounds.riv',
-              fit: BoxFit.cover,
-              onInit: _onRiveInit,
-            ),
-          ),
-          const Align(
-            alignment: Alignment.topCenter,
-            child: Padding(
-              padding: EdgeInsets.all(16.0),
-              child: Text(
-                'Sound on!',
-                style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
-              ),
-            ),
-          ),
-        ],
-      ),
-    );
-  }
-}

example/lib/main.dart

@@ -9,7 +9,6 @@ import 'package:rive_example/custom_cached_asset_loading.dart';
 import 'package:rive_example/carousel.dart';
 import 'package:rive_example/custom_controller.dart';
 import 'package:rive_example/event_open_url_button.dart';
-import 'package:rive_example/event_sounds.dart';
 import 'package:rive_example/event_star_rating.dart';
 import 'package:rive_example/example_state_machine.dart';
 import 'package:rive_example/liquid_download.dart';
@@ -77,7 +76,6 @@ class _RiveExampleAppState extends State<RiveExampleApp> {
     const _Page('Asset Loading', CustomAssetLoading()),
     const _Page('Cached Asset Loading', CustomCachedAssetLoading()),
     const _Page('Event Open URL Button', EventOpenUrlButton()),
-    const _Page('Event Sounds', EventSounds()),
     const _Page('Event Star Rating', EventStarRating()),
     const _Page('Rive Audio', RiveAudioExample()),
     const _Page('Rive Audio [Out-of-Band]', RiveAudioOutOfBandExample()),

example/pubspec.yaml

@@ -14,7 +14,6 @@ dependencies:
   rive:
     path: ../
   http:
-  just_audio: ^0.9.34
   url_launcher: ^6.1.14
 
 dev_dependencies: