cli.confirm should allow for defaults

[TranquilMarmot]

It's common in CLIs to have a yes/no prompt with a default, i.e. (Y/n) implies that just pressing enter will default to "yes".

It would be nice to have an option for cli.confirm to be able to accept a default answer (this would probably also be nice for cli.prompt)

[RasPhilCo]

Good idea! Should be a straightforward PR if someone wants to pick this up.

[AaronConlon]

we need it.