[Mono.Android] Fix mapping of Android.Content.PM.ForegroundService (#5650)

The following [`android.app.Service`][0] methods:

  * [`int  getForegroundServiceType()`][1]
  * [`void startForeground(int id, Notification notification, int foregroundServiceType)`][2]

were not being bound within `Mono.Android.dll`, because of the
following warnings emitted during the `src/Mono.Android` build:

	warning BG8700: Unknown return type 'Android.App.ForegroundService' for member 'Android.App.Service.GetForegroundServiceType ()'.
	warning BG8800: Unknown parameter type 'Android.App.ForegroundService' for member 'Android.App.Service.StartForeground (int, Android.App.Notification, Android.App.ForegroundService)'.

The cause of these warnings is that the `Service` methods were
"enumified" to use a C# enum instead of an `int`, and a nonexistent
`Android.App.ForegroundService` type was specified in `methodmap.csv`.

Fix these warnings by specifying the correct type
`Android.Content.PM.ForegroundService`.  This will ensure that these
methods are bound within `Mono.Android.dll`:

	partial class Service {
	    Android.Content.PM.ForegroundService    GetForegroundServiceType();
	    void                                    StartForeground(int, Android.App.Notification, Android.Content.PM.ForegroundService);
	}

[0]: https://developer.android.com/reference/android/app/Service
[1]: https://developer.android.com/reference/android/app/Service#getForegroundServiceType()
[2]: https://developer.android.com/reference/android/app/Service#startForeground(int,%20android.app.Notification,%20int)

build-tools/enumification-helpers/methodmap.ext.csv

@@ -1909,8 +1909,8 @@
 29, android.app, AppOpsManager, startWatchingMode, flags, Android.App.Admin.WatchForeground
 29, android.app, RemoteInput.Builder, setEditChoicesBeforeSending, editChoicesBeforeSending, Android.App.EditChoices
 29, android.app, RemoteInput, getEditChoicesBeforeSending, return, Android.App.EditChoices
-29, android.app, Service, getForegroundServiceType, return, Android.App.ForegroundService
-29, android.app, Service, startForeground, foregroundServiceType, Android.App.ForegroundService
+29, android.app, Service, getForegroundServiceType, return, Android.Content.PM.ForegroundService
+29, android.app, Service, startForeground, foregroundServiceType, Android.Content.PM.ForegroundService
 // Cannot change this at this state.
 // 27, android.app, WallpaperManager.OnColorsChangedListener, onColorsChanged, which, Android.App.WallpaperManagerFlags
 29, android.content, Context, bindIsolatedService, flags, Android.App.Bind

src/Mono.Android/methodmap.csv

@@ -2519,8 +2519,8 @@
 29, android.app, AppOpsManager, startWatchingMode, flags, Android.App.WatchForeground
 29, android.app, RemoteInput.Builder, setEditChoicesBeforeSending, editChoicesBeforeSending, Android.App.EditChoices
 29, android.app, RemoteInput, getEditChoicesBeforeSending, return, Android.App.EditChoices
-29, android.app, Service, getForegroundServiceType, return, Android.App.ForegroundService
-29, android.app, Service, startForeground, foregroundServiceType, Android.App.ForegroundService
+29, android.app, Service, getForegroundServiceType, return, Android.Content.PM.ForegroundService
+29, android.app, Service, startForeground, foregroundServiceType, Android.Content.PM.ForegroundService
 // Cannot change this at this state.
 // 27, android.app, WallpaperManager.OnColorsChangedListener, onColorsChanged, which, Android.App.WallpaperManagerFlags
 29, android.content, Context, bindIsolatedService, flags, Android.App.Bind