Start audio player using foreground service API on Android 26+

On API 26+ (Oreo, 8.0) running background services is restricted
by power saving mechanisms, causing occasional IllegalStateException
when service intent is rejected by the OS.

Migrate to startForegroundService API to mitigate this problem.
Audio player service is foreground by design.

Fixes #6665

Signed-off-by: Chris Narkiewicz <hello@ezaquarii.com>

src/main/java/com/nextcloud/client/media/PlayerServiceConnection.kt

@@ -23,6 +23,7 @@ import android.content.ComponentName
 import android.content.Context
 import android.content.Intent
 import android.content.ServiceConnection
+import android.os.Build
 import android.os.IBinder
 import android.widget.MediaController
 import com.nextcloud.client.account.User
@@ -56,20 +57,20 @@ class PlayerServiceConnection(private val context: Context) : MediaController.Me
         i.putExtra(PlayerService.EXTRA_AUTO_PLAY, playImmediately)
         i.putExtra(PlayerService.EXTRA_START_POSITION_MS, position)
         i.action = PlayerService.ACTION_PLAY
-        context.startService(i)
+        startForegroundService(i)
     }
 
     fun stop(file: OCFile) {
         val i = Intent(context, PlayerService::class.java)
         i.putExtra(PlayerService.EXTRA_FILE, file)
         i.action = PlayerService.ACTION_STOP_FILE
-        context.startService(i)
+        startForegroundService(i)
     }
 
     fun stop() {
         val i = Intent(context, PlayerService::class.java)
         i.action = PlayerService.ACTION_STOP
-        context.startService(i)
+        startForegroundService(i)
     }
 
     private val connection = object : ServiceConnection {
@@ -131,4 +132,12 @@ class PlayerServiceConnection(private val context: Context) : MediaController.Me
     }
 
     // endregion
+
+    private fun startForegroundService(i: Intent) {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            context.startForegroundService(i)
+        } else {
+            context.startService(i)
+        }
+    }
 }