[Request] Pass custom `stdin` to prompts

[EGOIST]

Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

there's no way to pass a custom stdin to @clack/prompts

Describe the solution you'd like
A clear and concise description of what you want to happen.
add an option for stdin

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.