feat: extensive settings for media controls through notification (#28)

* feat: add notification settings customisation options

* feat: add notification settings page and update routing

lib/features/player/core/init.dart

@@ -0,0 +1,62 @@
+import 'package:audio_service/audio_service.dart';
+import 'package:audio_session/audio_session.dart';
+import 'package:just_audio_background/just_audio_background.dart'
+    show JustAudioBackground, NotificationConfig;
+import 'package:just_audio_media_kit/just_audio_media_kit.dart'
+    show JustAudioMediaKit;
+import 'package:vaani/settings/app_settings_provider.dart';
+import 'package:vaani/settings/models/app_settings.dart';
+
+Future<void> configurePlayer() async {
+  // for playing audio on windows, linux
+  JustAudioMediaKit.ensureInitialized();
+
+  // for configuring how this app will interact with other audio apps
+  final session = await AudioSession.instance;
+  await session.configure(const AudioSessionConfiguration.speech());
+
+  final appSettings = loadOrCreateAppSettings();
+
+  // for playing audio in the background
+  await JustAudioBackground.init(
+    androidNotificationChannelId: 'com.vaani.bg_demo.channel.audio',
+    androidNotificationChannelName: 'Audio playback',
+    androidNotificationOngoing: true,
+    androidStopForegroundOnPause: true,
+    androidNotificationChannelDescription: 'Audio playback in the background',
+    androidNotificationIcon: 'drawable/ic_stat_notification_logo',
+    rewindInterval: appSettings.notificationSettings.rewindInterval,
+    fastForwardInterval: appSettings.notificationSettings.fastForwardInterval,
+    androidShowNotificationBadge: false,
+    notificationConfigBuilder: (state) {
+      final controls = [
+        if (appSettings.notificationSettings.mediaControls
+                .contains(NotificationMediaControl.skipToPreviousChapter) &&
+            state.hasPrevious)
+          MediaControl.skipToPrevious,
+        if (appSettings.notificationSettings.mediaControls
+            .contains(NotificationMediaControl.rewind))
+          MediaControl.rewind,
+        if (state.playing) MediaControl.pause else MediaControl.play,
+        if (appSettings.notificationSettings.mediaControls
+            .contains(NotificationMediaControl.fastForward))
+          MediaControl.fastForward,
+        if (appSettings.notificationSettings.mediaControls
+                .contains(NotificationMediaControl.skipToNextChapter) &&
+            state.hasNext)
+          MediaControl.skipToNext,
+        if (appSettings.notificationSettings.mediaControls
+            .contains(NotificationMediaControl.stop))
+          MediaControl.stop,
+      ];
+      return NotificationConfig(
+        controls: controls,
+        systemActions: const {
+          MediaAction.seek,
+          MediaAction.seekForward,
+          MediaAction.seekBackward,
+        },
+      );
+    },
+  );
+}