Extend DSA Reads to compute plan name and version from plan ID (#20)

* Extend Read to compute plan name and version from plan ID

* Lint

* Fix error handling; Pass client to loadPlanNameAndVersion

* Change error to warning

* Replicate to other DSA

* Update acc tests to test import of plan name and version

stackit/services/postgresql/postgresql_acc_test.go

@@ -144,9 +144,8 @@ func TestAccPostgreSQLResource(t *testing.T) {
 					}
 					return fmt.Sprintf("%s,%s", testutil.ProjectId, instanceId), nil
 				},
-				ImportState:             true,
-				ImportStateVerify:       true,
-				ImportStateVerifyIgnore: []string{"plan_name", "version"},
+				ImportState:       true,
+				ImportStateVerify: true,
 			},
 			{
 				ResourceName: "stackit_postgresql_credentials.credentials",