Add custom routes for directpath to net-vpc module (#2966)

* add custom routes for directpath to net-vpc module

* blueprint tests

* blueprint tests

* blueprint tests

* fast tests

* tfdoc

* module examples

modules/cloudsql-instance/README.md

@@ -24,6 +24,7 @@ Note that this module assumes that some options are the same for both the primar
 <!-- END TOC -->
 
 ## Examples
+
 ### Simple example
 
 This example shows how to setup a project, VPC and a standalone Cloud SQL instance.
@@ -77,7 +78,7 @@ module "db" {
   gcp_deletion_protection       = false
   terraform_deletion_protection = false
 }
-# tftest modules=3 resources=15 inventory=simple.yaml isolated e2e
+# tftest modules=3 resources=16 inventory=simple.yaml isolated e2e
 ```
 
 ### Cross-regional read replica
@@ -227,7 +228,7 @@ module "db" {
   terraform_deletion_protection = false
 }
 
-# tftest modules=4 resources=21 isolated e2e
+# tftest modules=4 resources=22 isolated e2e
 ```
 
 ### Instance with PSC enabled