[AC-358] Server changes for self host subscription page changes (#2826)

* [AC-358] Add constant for grace period length

* [AC-358] Add SubscriptionExpiration to OrganizationLicense.cs and increment Current_License_File_Version

* [AC-358] Update org subscription response model

- Add new SelfHostSubscriptionExpiration field that does not include a grace period
- Add optional License argument to constructor for self host responses
- Use the License, if available, to populate the expiration/subscription expiration fields
- Maintain backwards compatability by falling back to organization expiration date

* [AC-358] Read organization license file for self hosted subscription response

* [AC-358] Decrement current license file version and add comment documenting why

* [AC-358] Clarify name for new expiration without grace period field

src/Core/Constants.cs

@@ -13,6 +13,12 @@ public static class Constants
     public const long FileSize501mb = 501L * 1024L * 1024L;
     public const string DatabaseFieldProtectorPurpose = "DatabaseFieldProtection";
     public const string DatabaseFieldProtectedPrefix = "P|";
+
+    /// <summary>
+    /// Default number of days an organization has to apply an updated license to their self-hosted installation after
+    /// their subscription has expired.
+    /// </summary>
+    public const int OrganizationSelfHostSubscriptionGracePeriodDays = 60;
 }
 
 public static class TokenPurposes