feat(iaas): support for v2 API (#1070)

relates to STACKITTPR-313

examples/resources/stackit_network_area_region/resource.tf

@@ -0,0 +1,18 @@
+resource "stackit_network_area_region" "example" {
+  organization_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+  network_area_id = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
+  ipv4 = {
+    transfer_network = "10.1.2.0/24"
+    network_ranges = [
+      {
+        prefix = "10.0.0.0/16"
+      }
+    ]
+  }
+}
+
+# Only use the import statement, if you want to import an existing network area region
+import {
+  to = stackit_network_area_region.import-example
+  id = "${var.organization_id},${var.network_area_id},${var.region}"
+}