Update private preferences for version tracking & secure (#158)

Xamarin.Essentials/Preferences/Preferences.shared.cs

@@ -2,6 +2,9 @@
 {
     public static partial class Preferences
     {
+        internal static string PrivatePreferencesSharedName =>
+            $"{AppInfo.PackageName}.xamarinessentials";
+
         public static bool ContainsKey(string key) =>
             PlatformContainsKey(key, null);
 

Xamarin.Essentials/SecureStorage/SecureStorage.shared.cs

@@ -4,8 +4,7 @@ namespace Xamarin.Essentials
 {
     public static partial class SecureStorage
     {
-        static string Alias =>
-            $"{AppInfo.PackageName}.Xamarin.Essentials";
+        internal static readonly string Alias = Preferences.PrivatePreferencesSharedName;
 
         public static Task<string> GetAsync(string key)
             => PlatformGetAsync(key);

Xamarin.Essentials/VersionTracking/VersionTracking.shared.cs

@@ -11,7 +11,7 @@ namespace Xamarin.Essentials
         const string versionsKey = "VersionTracking.Versions";
         const string buildsKey = "VersionTracking.Builds";
 
-        static readonly string sharedName = $"{AppInfo.PackageName}.Xamarin.Essentials";
+        static readonly string sharedName = Preferences.PrivatePreferencesSharedName;
 
         static Dictionary<string, List<string>> versionTrail;