Support Nushell when resolving the shell environment

[EmilyGraceSeville7cf]

Does this issue occur when all extensions are disabled?: Yes/No

VS Code Version:

Version: 1.73.1
Commit: 6261075646f055b99068d3688932416f2346dd3b
Date: 2022-11-09T03:54:53.913Z
Electron: 19.0.17
Chromium: 102.0.5005.167
Node.js: 16.14.2
V8: 10.2.154.15-electron.0
OS: Linux x64 5.19.0-21-generic
Sandboxed: No

OS Version: Ubuntu 22.10 (Lubuntu)

Steps to Reproduce:

1. Add /home/emilyseville7cfg/.cargo/bin/nu to /etc/shells
2. Do sudo chsh --shell /home/emilyseville7cfg/.cargo/bin/nu
3. Relogin to apply changes
4. Start VS Code
5. Obtain Unable to resolve your shell environment: Unexpected exit code from spawned shell (code 1, signal null) error

[joaomoreno]

This needs to be changed to work with Nushell.