feat(externalnetwork): vpn support for external networks

[roleyfoley]

Description

AWS implementation of hamlet-io/engine#1328
Initial external network implementation is for an external network with VPN connection to a network or router

Motivation and Context

Supports VPN based connections to AWS VPC services

How Has This Been Tested?

Tested in local deployment

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves the structure or operation of the implementation)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Followup Actions

• None

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• None of the above.