[Module Proposal]: `avm-ptn-azure-aws-s2s-vpn`

### Check for previous/existing GitHub issues/module proposals

- [x] I have checked for previous/existing GitHub issues/module proposals.

### Check this module doesn't already exist in the module indexes

- [x] I have checked for that this module doesn't already exist in the module indexes.

### Bicep or Terraform?

Terraform

### Module Classification?

I'm not sure, please advise

### Module Name

terraform-azurerm-avm-ptn-azure-aws-s2s-vpn

### Module Details

An Azure Verified Module (AVM) pattern module that automates cross-cloud Site-to-Site VPN connectivity between Azure and AWS. Creates an active-active Azure VPN Gateway with BGP over APIPA and 4 redundant IPsec tunnels. Supports four AWS-side deployment scenarios: greenfield (new VPC + VPG), Transit Gateway (multi-VPC hub), existing VPC (add VPG), and existing VPG (tunnel-only). Based on the AWS reference architecture for private network connectivity between Azure and AWS.

### Do you want to be the owner of this module?

Yes

### Module Owner's GitHub Username (handle)

ShironB

### (Optional) Secondary Module Owner's GitHub Username (handle)

_No response_