[Provider] Server entities and models (#1370)

* Mock out provider models and service

* Implement CreateAsync, CompleteSetupAsync, UpdateAsync, InviteUserAsync and ResendInvitesAsync

* Implement AcceptUserAsync and ConfirmUsersAsync

* Implement SaveUserAsync and DeleteUserAsync

* Add email templates

* Add admin operations for providers

* Fix mail template names

* Rename roles

* Verify provider has provideradmin

* Add self hosted check to admin controller

* Resolve review comments

* Update sql queries

* Change create provider to use email instead of userId

src/Sql/dbo/Stored Procedures/ProviderUser_ReadByProviderId.sql

@@ -1,5 +1,6 @@
 CREATE PROCEDURE [dbo].[ProviderUser_ReadByProviderId]
-    @ProviderId UNIQUEIDENTIFIER
+    @ProviderId UNIQUEIDENTIFIER,
+    @Type TINYINT
 AS
 BEGIN
     SET NOCOUNT ON
@@ -10,4 +11,5 @@ BEGIN
         [dbo].[ProviderUserView]
     WHERE
         [ProviderId] = @ProviderId
+        AND [Type] = COALESCE(@Type, [Type])
 END