VPC Network Tier Permissions within domain

##### ISSUE TYPE
* Improvement Request

##### COMPONENT NAME

VR, Network Tier

##### CLOUDSTACK VERSION

4.18.0.0

##### CONFIGURATION

It is unable to grant permission for VPC Tier network to users within the same domain.

##### STEPS TO REPRODUCE

I created VPC and network tier using user1 on domain xyz, user2 (domain admin for xyz domain) couldn't create instance with created network tier. However networks and VPC visible for user2

##### EXPECTED RESULTS
Allow permissions for network tier as for L2 networks

Start by reproducing the VPC and network-tier setup from the issue in CloudStack 4.18 with user1 and user2 in the same domain, then compare its permission behavior with L2 networks. Done means the domain admin can create an instance using the network tier created by user1, while the VPC and network tier remain visible as described.

Written by the indexing model from the issue text.