Support `networkingMode=mirrored` while IPv6 is disabled via Registry

Nobody has claimed this yet.

**Is your feature request related to a problem? Please describe.**

In previous issues we discovered that having `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\DisabledComponents` set to `0xFF / 255` is problematic when `networkingMode=mirrored` is used - networking Mode simply falls back to the bridged default networking under windows. Sometimes removing or setting to `0x20` is helpful and users are permanently happy. Sometimes that is not enough - [IPv6 Registry Setting related Issues ](https://github.com/microsoft/WSL/issues?q=DisabledComponents).
It seems that - either because of past windows vulnerability mitigations or caused by a VPN Client - a lot of folks do not have the ability to reliably set that registry value without it being reset the next reboot.

**Describe the solution you'd like**
It would be neat if WSL in this case would just do the mirrored mode networking without IPv6.

**Describe alternatives you've considered**
It'd be neat if Microsoft could do some work to get IT administrators to get rid of the vulnerability mitigation when it is no longer needed though that isn't the WSL teams problem to deal with.

Start by tracing how WSL handles networkingMode=mirrored when the Windows Tcpip6 DisabledComponents registry value is set to 0xFF or 255. Define the expected behavior for mirrored networking with IPv6 disabled, then verify it across the affected registry settings and reboot scenarios.

Written by the indexing model from the issue text.