[PM-27280] Support v2 encryption on key-connector signups (#6712)

* account v2 registration for key connector

* use new user repository functions

* test coverage

* integration test coverage

* documentation

* code review

* missing test coverage

* fix failing test

* failing test

* incorrect ticket number

* moved back request model to Api, created dedicated data class in Core

* sql stored procedure type mismatch, simplification

* key connector authorization handler

util/Migrator/DbScripts/2025-12-17_00_User_UpdateKeyConnectorUserKey.sql

@@ -0,0 +1,29 @@
+CREATE OR ALTER PROCEDURE [dbo].[User_UpdateKeyConnectorUserKey]
+    @Id UNIQUEIDENTIFIER,
+    @Key VARCHAR(MAX),
+    @Kdf TINYINT,
+    @KdfIterations INT,
+    @KdfMemory INT,
+    @KdfParallelism INT,
+    @UsesKeyConnector BIT,
+    @RevisionDate DATETIME2(7),
+    @AccountRevisionDate DATETIME2(7)
+AS
+BEGIN
+    SET NOCOUNT ON
+
+UPDATE
+    [dbo].[User]
+SET
+    [Key] = @Key,
+    [Kdf] = @Kdf,
+    [KdfIterations] = @KdfIterations,
+    [KdfMemory] = @KdfMemory,
+    [KdfParallelism] = @KdfParallelism,
+    [UsesKeyConnector] = @UsesKeyConnector,
+    [RevisionDate] = @RevisionDate,
+    [AccountRevisionDate] = @AccountRevisionDate
+WHERE
+    [Id] = @Id
+END
+GO