Add support to specify VLAN # when using Bridged Network Mode

Trying to use Bridged mode in WSL2 on Windows Server 2025 and need to use a VLAN number.
This is a Hyper-V server running several other Windows VMs, each has their Virtual NICs on different VLANs.

Need WSL to use a VLAN on it's virtual NIC that is on the virtual switch like other VMs that are configurable in HyperV Manager.

Maybe something in .wslconfig

```
[wsl2]
networkMode=bridged
vmSwitch="VirtualSwitch"
networkBridgedVlan=123

```

Some AI searches offered some workarounds but nothing works.

Using a native VLAN on the interface would disrupt other VMs already using the VLAN.

Windows Server 2025 does not support mirrored mode.

Thanks,

Start by tracing how WSL reads the [wsl2] .wslconfig settings for networkMode and vmSwitch, then inspect the bridged networking path. Done means a VLAN value such as networkBridgedVlan=123 is accepted and applied to the WSL virtual NIC on the selected Hyper-V switch, with coverage for the requested configuration.

Written by the indexing model from the issue text.