CfnVPNConnection: Support IPv6 Inside tunnel

### Describe the feature

It seems that ec2.CfnVPNConnection does not support IPv6 (or is not documented).
I would like to be able to create IPv6 site-to-site VPNs via CDK but the standard SDK "TunnelInsideIpVersion" is not available.
Example of how this is available in Boto3: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/ec2.html#EC2.Client.create_vpn_connection

Using a custom resource to create VPNs is really not ideal because VPNs take a long time to become available and thus probably require asynchronous checking.

Can we please enable IPv6 site-to-site VPNs in CDK?

### Use Case

Connecting site-to-side with IPv6 internal addresses/traffic.

### Proposed Solution

Add TunnelInsideIpVersion and TunnelInsideIpv6Cidr to tunnel options.

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### CDK version used

2.46.0 (build 5a0595e)

### Environment details (OS name and version, etc.)

MacOS Monterey 12.4

Start at the CfnVPNConnection entry point and its tunnel options, then compare the linked Boto3 create_vpn_connection reference for the IPv6 property names. Done means TunnelInsideIpVersion and TunnelInsideIpv6Cidr are available for configuring IPv6 site-to-site VPNs through CDK.

Written by the indexing model from the issue text.