[PS-1312] Migration to android12 and new splashscreen (#2063)

* [PS-1312] Updated Android Target and Framework to Android12 and updated new SplashScreen for Android12

* PS-1312 Changed PendingIntents mutability

* PS-1312 Removed unused imports

* PS-1312 Added method to helper to add mutability option according to Android version

* PS-1312 Renamed helper method AddPendingIntentMutability and fixed validation

* PS-1312 Improved PendingIntentMutability method from helper readability and naming

src/Android/Utilities/AndroidHelpers.cs

@@ -1,6 +1,8 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
+using Android.App;
 using Android.Content;
+using Android.OS;
 using Android.Provider;
 using Bit.App.Utilities;
 
@@ -47,5 +49,22 @@ namespace Bit.Droid.Utilities
                 await AppHelpers.SetPreconfiguredSettingsAsync(dict);
             }
         }
+
+        public static PendingIntentFlags AddPendingIntentMutabilityFlag(PendingIntentFlags pendingIntentFlags, bool isMutable)
+        {
+            //Mutable flag was added on API level 31
+            if (isMutable && Build.VERSION.SdkInt >= BuildVersionCodes.S)
+            {
+                return pendingIntentFlags | PendingIntentFlags.Mutable;
+            }
+
+            //Immutable flag was added on API level 23
+            if (!isMutable && Build.VERSION.SdkInt >= BuildVersionCodes.M)
+            {
+                return pendingIntentFlags | PendingIntentFlags.Immutable;
+            }
+
+            return pendingIntentFlags;
+        }
     }
 }