Windows - UNC Path Support via `npm.ps1`

[mribbons]

What is the problem this feature will solve?

npm.cmd fails on Windows in UNC (And WSL) paths, because cmd.exe doesn't support UNC paths as cwd: https://github.com/npm/cli/issues/6280

What is the feature you are proposing to solve the problem?

This PR partially resolves the problem, but we need more info, as requested by @lukekarrys:

https://github.com/npm/cli/pull/6548

Would you be able to open an issue or PR on https://github.com/nodejs/node to get feedback on how the Windows installers work, and if it would be appropriate for npm to ship these ps1 scripts in our bin/ dir and have them picked up by the installer?

What alternatives have you considered?

No response