feat: added gcp_na support

Author: harshithad0703

src/main/java/com/contentstack/sdk/Region.java

@@ -25,4 +25,8 @@ public enum Region {
      * Azure na region.
      */
     AZURE_NA,
+    /**
+     * Gcp na region.
+     */
+    GCP_NA,
 }

src/test/java/com/contentstack/sdk/TestClient.java

@@ -47,6 +47,14 @@ public static Marketplace getMarketplaceAzureEu() {
                 .build();
     }
 
+    public static Marketplace getMarketplaceGcpNa() {
+        return new Marketplace
+                .Builder(TestClient.ORGANIZATION_UID)
+                .host(HOST)
+                .region(Region.GCP_NA)
+                .build();
+    }
+
 
     public static Marketplace getMarketplaceWithLogin() {
         return new Marketplace