fix(android): Avoid calling onDuration on position event (closes #136) (#1460)

# Description

Unlike on other platforms, onDuration is constantly called on Android.
This PR avoids calling onDuration on every position event.
OnDuration is still once called with the correct duration after having
prepared the source.

Author: Gustl22

packages/audioplayers/example/.metadata

@@ -4,7 +4,7 @@
 # This file should be version controlled.
 
 version:
-  revision: ffccd96b62ee8cec7740dab303538c5fc26ac543
+  revision: 62bd79521d8d007524e351747471ba66696fc2d4
   channel: stable
 
 project_type: app
@@ -13,11 +13,26 @@ project_type: app
 migration:
   platforms:
     - platform: root
-      create_revision: ffccd96b62ee8cec7740dab303538c5fc26ac543
-      base_revision: ffccd96b62ee8cec7740dab303538c5fc26ac543
+      create_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+      base_revision: 62bd79521d8d007524e351747471ba66696fc2d4
     - platform: android
-      create_revision: ffccd96b62ee8cec7740dab303538c5fc26ac543
-      base_revision: ffccd96b62ee8cec7740dab303538c5fc26ac543
+      create_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+      base_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+    - platform: ios
+      create_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+      base_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+    - platform: linux
+      create_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+      base_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+    - platform: macos
+      create_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+      base_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+    - platform: web
+      create_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+      base_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+    - platform: windows
+      create_revision: 62bd79521d8d007524e351747471ba66696fc2d4
+      base_revision: 62bd79521d8d007524e351747471ba66696fc2d4
 
   # User provided section
 

packages/audioplayers_android/android/src/main/kotlin/xyz/luan/audioplayers/AudioplayersPlugin.kt

@@ -290,9 +290,7 @@ class AudioplayersPlugin : FlutterPlugin, IUpdateCallback {
                     continue
                 }
                 isAnyPlaying = true
-                val duration = player.getDuration()
                 val time = player.getCurrentPosition()
-                player.eventHandler.success("audio.onDuration", hashMapOf("value" to (duration ?: 0)))
                 player.eventHandler.success("audio.onCurrentPosition", hashMapOf("value" to (time ?: 0)))
             }
             if (isAnyPlaying) {