Virtual network connection for private runners

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Infrastructure as Code Type? (Required)

bicep

### Starter Module? (Required)

terraform - platform_landing_zone

### Use Case (Required)

Would it be possible to include a virtual network connection from the private runner vnet to the hub? This way we can also use the private runners created by the bootstrap to deploy our application landing zones and all the resources. Now this a standalone vent.

### Proposed Solution (Required)

Would it be possible to include a virtual network connection from the private runner vnet to the hub? This way we can also use the private runners created by the bootstrap to deploy our application landing zones and all the resources. Now this a standalone vent.

### Important Factoids (Optional)

_No response_

### References (Optional)

_No response_

Start in the terraform platform_landing_zone starter module and trace how the private runner VNet and hub are defined. Determine the required connection and its configuration boundaries from the existing infrastructure. Done means the bootstrap-created private runners can reach the hub and deploy application landing zones and their resources.

Written by the indexing model from the issue text.