Add ability to deny access in Network Security Group rules

[Gonçalo Rodrigues]

Right now, priority is only used in Azure and we don't expose any way to deny traffic.
We need to:

• Expose a way to deny traffic in a NSG, similarly to how azure does it
• Make sure priority is respected in both AWS and AZURE

[Sankeerthan Kasilingam]

Hi @goncalo-rodrigues,
If It's open to the community, Can I try to fix it?