feat: SQL server beta and templates refactoring (#32)

## Description

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At least please give us some description what you are trying to achieve and why your change is needed. -->

relates to #1234

## Checklist

- [ ] Issue was linked above
- [ ] Code format was applied: `make fmt`
- [ ] Examples were added / adjusted (see `examples/` directory)
- [x] Docs are up-to-date: `make generate-docs` (will be checked by CI)
- [ ] Unit tests got implemented or updated
- [ ] Acceptance tests got implemented or updated (see e.g. [here](f5f99d1709/stackit/internal/services/dns/dns_acc_test.go))
- [x] Unit tests are passing: `make test` (will be checked by CI)
- [x] No linter issues: `make lint` (will be checked by CI)

Reviewed-on: #32
Reviewed-by: Andre_Harms <andre.harms@stackit.cloud>
Co-authored-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>
Co-committed-by: Marcel S. Henselin <marcel.henselin@stackit.cloud>

stackit/internal/services/sqlserverflexbeta/user/resources_gen/user_resource_gen.go

@@ -0,0 +1,111 @@
+// Code generated by terraform-plugin-framework-generator DO NOT EDIT.
+
+package sqlserverflexbeta
+
+import (
+	"context"
+	"github.com/hashicorp/terraform-plugin-framework-validators/stringvalidator"
+	"github.com/hashicorp/terraform-plugin-framework/schema/validator"
+	"github.com/hashicorp/terraform-plugin-framework/types"
+
+	"github.com/hashicorp/terraform-plugin-framework/resource/schema"
+)
+
+func UserResourceSchema(ctx context.Context) schema.Schema {
+	return schema.Schema{
+		Attributes: map[string]schema.Attribute{
+			"default_database": schema.StringAttribute{
+				Optional:            true,
+				Computed:            true,
+				Description:         "The default database for a user of the instance.",
+				MarkdownDescription: "The default database for a user of the instance.",
+			},
+			"host": schema.StringAttribute{
+				Computed:            true,
+				Description:         "The host of the instance in which the user belongs to.",
+				MarkdownDescription: "The host of the instance in which the user belongs to.",
+			},
+			"id": schema.Int64Attribute{
+				Computed:            true,
+				Description:         "The ID of the user.",
+				MarkdownDescription: "The ID of the user.",
+			},
+			"instance_id": schema.StringAttribute{
+				Optional:            true,
+				Computed:            true,
+				Description:         "The ID of the instance.",
+				MarkdownDescription: "The ID of the instance.",
+			},
+			"password": schema.StringAttribute{
+				Computed:            true,
+				Description:         "The password for the user.",
+				MarkdownDescription: "The password for the user.",
+			},
+			"port": schema.Int64Attribute{
+				Computed:            true,
+				Description:         "The port of the instance in which the user belongs to.",
+				MarkdownDescription: "The port of the instance in which the user belongs to.",
+			},
+			"project_id": schema.StringAttribute{
+				Optional:            true,
+				Computed:            true,
+				Description:         "The STACKIT project ID.",
+				MarkdownDescription: "The STACKIT project ID.",
+			},
+			"region": schema.StringAttribute{
+				Optional:            true,
+				Computed:            true,
+				Description:         "The region which should be addressed",
+				MarkdownDescription: "The region which should be addressed",
+				Validators: []validator.String{
+					stringvalidator.OneOf(
+						"eu01",
+					),
+				},
+			},
+			"roles": schema.ListAttribute{
+				ElementType:         types.StringType,
+				Required:            true,
+				Description:         "A list containing the user roles for the instance.",
+				MarkdownDescription: "A list containing the user roles for the instance.",
+			},
+			"status": schema.StringAttribute{
+				Computed:            true,
+				Description:         "The current status of the user.",
+				MarkdownDescription: "The current status of the user.",
+			},
+			"uri": schema.StringAttribute{
+				Computed:            true,
+				Description:         "The connection string for the user to the instance.",
+				MarkdownDescription: "The connection string for the user to the instance.",
+			},
+			"user_id": schema.Int64Attribute{
+				Optional:            true,
+				Computed:            true,
+				Description:         "The ID of the user.",
+				MarkdownDescription: "The ID of the user.",
+			},
+			"username": schema.StringAttribute{
+				Required:            true,
+				Description:         "The name of the user.",
+				MarkdownDescription: "The name of the user.",
+			},
+		},
+	}
+}
+
+type UserModel struct {
+	DefaultDatabase types.String `tfsdk:"default_database"`
+	Host            types.String `tfsdk:"host"`
+	Id              types.Int64  `tfsdk:"id"`
+	InstanceId      types.String `tfsdk:"instance_id"`
+	Password        types.String `tfsdk:"password"`
+	Port            types.Int64  `tfsdk:"port"`
+	ProjectId       types.String `tfsdk:"project_id"`
+	Region          types.String `tfsdk:"region"`
+	Roles           types.List   `tfsdk:"roles"`
+	Status          types.String `tfsdk:"status"`
+	Uri             types.String `tfsdk:"uri"`
+	UserId          types.Int64  `tfsdk:"user_id"`
+	Username        types.String `tfsdk:"username"`
+}