[Module Proposal]: `avm/ptn/network/vwan-connected-vnets`

### 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?

Bicep

### Module Classification?

Pattern Module

### Module Name

avm/ptn/network/vwan-connected-vnets

### Module Details

Currently we have some bicep templates that we used to create VNET and VMs that are connected to a hub of Virtual WAN. The template assumes that there is a VWAN instance with its hubs already deployed.

Our deployment takes care of creating the VNET/VM and vWAN Connection to an existing hub so that the VM are network routable one the deployment is completed. The deployment also Domain Join the VMs and managed credentials via private traffic to a KeyVault.

Edit (from internal discussions):
This patterns provides a way for teams using a centralized infra (not managed by them) to connect (VNETs/VMs, Hub connection) resources to it so they can build their services using other shared services that reside in the centralized infra (FW, ER, P2S, etc...).

This module will leverage the following resources (resource modules that encapsulate these):
- Microsoft.Network/virtualNetworks
- Microsoft.KeyVault/vaults
- Microsoft.Storage/storageAccounts
- Microsoft.Resources/deploymentScripts
- Microsoft.ManagedIdentity/userAssignedIdentities
- Microsoft.Network/bastionHosts

This module will leverage the following resources directly (without using a resource module):
- Microsoft.Network/virtualHubs/hubVirtualNetworkConnections

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

Yes

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

juancj

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

ericscheffler