Feat: alpha sqlserver user (#12)

* fix: remove unused attribute types and functions from backup models

* fix: update API client references to use sqlserverflexalpha package

* fix: update package references to use sqlserverflexalpha and modify user data source model

* fix: add sqlserverflexalpha user data source to provider

* fix: add sqlserverflexalpha user resource and update related functionality

* chore: add stackit_sqlserverflexalpha_user resource and instance_id variable

* fix: refactor sqlserverflexalpha user resource and enhance schema with status and default_database

* chore: remove not needed service files

* chore: cleanup import in utils

* fix: provider name change

* fix: clone missing doc files

* fix: docs adjustments

* fix: docs CI scripts

* fix: docs naming

* fix: remove guides from docs

* fix: adjust examples

* fix: remove obsolete doc templates

* fix: docs adjustments

* fix: add missing doc file

* fix: temp rename file

---------

Co-authored-by: Andre Harms <andre.harms@stackit.cloud>
Co-authored-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>

stackit/provider_acc_test.go

@@ -1,3 +1,5 @@
+// Copyright (c) STACKIT
+
 package stackit_test
 
 import (