Mute files tracked by github

[belav]

We have a repo that has ~24,000 files. The Listing all files tracked by git group contains a massive output of all of those files.

I'm not sure how to test, but it appears that adding this option to git.ts would still work, and just mute the output to the console.

output = (await getExecOutput('git', ['ls-files', '-z'], { silent: true })).stdout

If the output is useful in some cases, maybe adding an option to mute it is also possible.