[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/Provider_Search.sql

@@ -0,0 +1,41 @@
+CREATE PROCEDURE [dbo].[Provider_Search]
+    @Name NVARCHAR(50),
+    @UserEmail NVARCHAR(256),
+    @Skip INT = 0,
+    @Take INT = 25
+WITH RECOMPILE
+AS
+BEGIN
+    SET NOCOUNT ON
+    DECLARE @NameLikeSearch NVARCHAR(55) = '%' + @Name + '%'
+
+    IF @UserEmail IS NOT NULL
+    BEGIN
+        SELECT
+            O.*
+        FROM
+            [dbo].[ProviderView] O
+        INNER JOIN
+            [dbo].[ProviderUser] OU ON O.[Id] = OU.[ProviderId]
+        INNER JOIN
+            [dbo].[User] U ON U.[Id] = OU.[UserId]
+        WHERE
+            (@Name IS NULL OR O.[Name] LIKE @NameLikeSearch)
+            AND U.[Email] = COALESCE(@UserEmail, U.[Email])
+        ORDER BY O.[CreationDate] DESC
+        OFFSET @Skip ROWS
+        FETCH NEXT @Take ROWS ONLY
+    END
+    ELSE
+    BEGIN
+        SELECT
+            O.*
+        FROM
+            [dbo].[ProviderView] O
+        WHERE
+            (@Name IS NULL OR O.[Name] LIKE @NameLikeSearch)
+        ORDER BY O.[CreationDate] DESC
+        OFFSET @Skip ROWS
+        FETCH NEXT @Take ROWS ONLY
+    END
+END