Slash commands in copilot cli and copilot cloud

[arqex]

Describe the feature or problem you'd like to solve

Custom slash commands should work in copilot cli and copilot cloud

Proposed solution

I have some custom prompts in .github/prompts that I can use in the VS code's copilot chat, but they don't work neither in the copilot cli or in the cloud.

If I use /review_pr 3211 in the vs chat, it reads .github/prompts/review_pr.prompt.md and follow the instructions. That doesn't happen in copilot cli or copilot cloud

Example prompts or workflows

/plan create a new controller
/review_pr 2341
/implement plan.md

Additional context

No response