`/share gist` can't handle certain formats well

[doggy8088]

Describe the bug

After using /share gist, I noticed that the gist contains some ASCII control characters. I think this could be handled better.

Affected version

GitHub Copilot CLI 0.0.400.

Steps to reproduce the behavior

1. Run any prompt
2. Send /share gist

Expected behavior

I expect to get a text that is not messed up.

Additional context

No response