startForegroundService() not allowed due to mAllowStartForeground false

Need to adopt Android 12 behavior changes, can't start foreground service from the background.

```
Fatal Exception: android.app.ForegroundServiceStartNotAllowedException: startForegroundService() not allowed due to mAllowStartForeground false:
service messenger.MainActivity.launcher.home.screen/com.liulishuo.filedownloader.services.FileDownloadService$SharedMainProcessService
at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel(ForegroundServiceStartNotAllowedException.java:54)
at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel(ForegroundServiceStartNotAllowedException.java:50)
at android.os.Parcel.readParcelable(Parcel.java:3345)
at android.os.Parcel.createExceptionOrNull(Parcel.java:2432)
at android.os.Parcel.createException(Parcel.java:2421)
at android.os.Parcel.readException(Parcel.java:2404)
at android.os.Parcel.readException(Parcel.java:2346)
at android.app.IActivityManager$Stub$Proxy.startService(IActivityManager.java:6968)
at android.app.ContextImpl.startServiceCommon(ContextImpl.java:1927)
at android.app.ContextImpl.startForegroundService(ContextImpl.java:1893)
at android.content.ContextWrapper.startForegroundService(ContextWrapper.java:798)
at g7.d.a(FileDownloadServiceSharedTransmit.java:8)
at g7.d.x099(:1)
at g7.c.x099(:2)
at g7.g.x022(FileDownloader.java:3)
at mymessenger.messaging.module.ui.main.MainFragment.onCreate(MainFragment.java:2)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:6)
at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:5)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:21)
at androidx.fragment.app.FragmentStore.moveToExpectedState(FragmentStore.java:3)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:57)
at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:3)
at androidx.fragment.app.FragmentManager.dispatchActivityCreated(FragmentManager.java:4)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(:4)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:6)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:1)
at com.android.launcher3.BaseActivity.onStart(BaseActivity.java:2)
at com.android.launcher3.BaseDraggingActivity.onStart(BaseDraggingActivity.java:1)
at com.android.launcher3.Launcher.onStart(Launcher.java:2)
at my.MainActivity.onStart(MainActivityLauncher.kt:1)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1455)
at android.app.Activity.performStart(Activity.java:8315)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:4060)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2438)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loopOnce(Looper.java:226)
at android.os.Looper.loop(Looper.java:313)
at android.app.ActivityThread.main(ActivityThread.java:8669)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135)

```

Start with the Android 12 foreground-service behavior and trace the call from MainFragment.onCreate through FileDownloader.java and FileDownloadServiceSharedTransmit.java. Reproduce the reported ForegroundServiceStartNotAllowedException and verify that the affected startup path no longer attempts an unallowed background service start.

Written by the indexing model from the issue text.