[AC-1753] Automatically assign provider's pricing to new organizations (#3513)

* Initial commit

* resolve pr comment

* adding some unit test

* Resolve pr comments

* Adding some unit test

* Resolve pr comment

* changes to find the bug

* revert back changes on admin

* Fix the failing Test

* fix the bug

src/Core/Constants.cs

@@ -29,6 +29,12 @@ public static class Constants
     /// Used by IdentityServer to identify our own provider.
     /// </summary>
     public const string IdentityProvider = "bitwarden";
+
+    /// <summary>
+    /// Date identifier used in ProviderService to determine if a provider was created before Nov 6, 2023.
+    /// If true, the organization plan assigned to that provider is updated to a 2020 plan.
+    /// </summary>
+    public static readonly DateTime ProviderCreatedPriorNov62023 = new DateTime(2023, 11, 6);
 }
 
 public static class AuthConstants