Add stub/mock for prompt::menu

[genebean]

Use Case

I have a plan with this block of code in it:

$menu = { 'y' => 'yes', 'n' => 'no' }
$selection = prompt::menu('Keep going?', $menu)

I want to be able to test this plan without having to dive under the hood of Bolt to figure out how to manually get the spec tests to not hang up when they reach the prompt::menu part.

I would also like to be able to test each option of the prompt.

Describe the Solution You Would Like

subs and mocks like exist for run_command() and the like.