[FIX] home widget count function and package source (#1252)

## Description

- Switched to pub.dev version of home_widget
- Replaced count home widget with getInstalledWidgets().

## Tests

mobile/lib/services/home_widget_service.dart

@@ -145,13 +145,7 @@ class HomeWidgetService {
   }
 
   Future<int> countHomeWidgets() async {
-    return await hw.HomeWidget.getWidgetCount(
-          name: 'SlideshowWidgetProvider',
-          androidName: 'SlideshowWidgetProvider',
-          qualifiedAndroidName: 'io.ente.photos.SlideshowWidgetProvider',
-          iOSName: 'SlideshowWidget',
-        ) ??
-        0;
+    return (await hw.HomeWidget.getInstalledWidgets()).length;
   }
 
   Future<void> clearHomeWidget() async {

mobile/pubspec.lock

@@ -933,12 +933,11 @@ packages:
   home_widget:
     dependency: "direct main"
     description:
-      path: "."
-      ref: main
-      resolved-ref: "49158ce4a517e87817dc84c6b96c00639281229a"
-      url: "https://github.com/ente-io/FlutterHomeWidget"
-    source: git
-    version: "0.4.1"
+      name: home_widget
+      sha256: "29565bfee4b32eaf9e7e8b998d504618b779a74b2b1ac62dd4dac7468e66f1a3"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.5.0"
   html:
     dependency: transitive
     description:

mobile/pubspec.yaml

@@ -91,10 +91,7 @@ dependencies:
   fluttertoast: ^8.0.6
   freezed_annotation: ^2.2.0
   google_nav_bar: ^5.0.5
-  home_widget:
-    git:
-      url: https://github.com/ente-io/FlutterHomeWidget
-      ref: main
+  home_widget: ^0.5.0
   html_unescape: ^2.0.0
   http: ^1.1.0
   image: ^4.0.17