feature: support font family picker in settings

[SimonSiefke]

Helps with #128355.

This is based on the Pull Request by @Tyriar and adds defaultSnippets for editor.fontFamily and terminal.integrated.fontFamily.

Testing

For testing, open the settings.json file and verify that completions for editor.fontFamily are visible.

Additional information

The completions for the settings ui are not supported, only the settings json editor.

[Tyriar]

Doesn't seem to work for me?

[SimonSiefke]

Hm, it worked for me on Linux and Windows.

When running the vscode from source in this branch, does await window.queryLocalFonts() in Chrome Devtools return a list of fonts?

I'm not quite sure why it's not working for you, perhaps something might be different on Macos?

[rzhao271]

I finally had some time to take a look at this PR and can confirm that it works on Windows. There are still some steps I'd like to take before approving this PR:

• [x] Update the PR with the latest changes from main
• [x] Test the PR on macOS
• [x] Test the PR on Linux

[rzhao271]

PR LGTM. Adding @deepak1556 to review app.ts