fix(windows): restore /editor support on Windows

[AbigailJixiangyuyu]

Issue for this PR

Closes #17117

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

This fixes /editor being unavailable on Windows.

I referred to the Node.js child_process documentation for Windows command
spawning behavior:
https://nodejs.org/api/child_process.html#spawning-bat-and-cmd-files-on-windows

According to that documentation, .bat and .cmd files may need to be launched
through a shell on Windows. In practice, commands such as $env:EDITOR = "code --wait"
could hang or fail to launch correctly when spawned without shell support.

This PR enables shell when launching the editor on Windows, so editor commands
like code --wait can be started correctly there and /editor works again.

How did you verify your code works?

Tested locally on Windows by running /editor and confirming:

• the editor opens correctly
• the edited content is saved and returned correctly

Screenshots / recordings

Included below.


Then close code.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

[Hona]

/review

[github-actions]

lgtm

[Hona]

later we might have issues with spaces in EDITOR or file name, but for now this is better