Network interfaces follow up

[just-be-dev]

This captures the follow up from #985.

• Show more details in the network interface minitable when creating custom NICs in the instance create form
• Implement the modal selection for making a NIC primary
• Address this comment if any design changes are required
• VPC and subnet name should be required in NIC create form #993

[david-crespo]

This is all already more or less done.