[feature] nimble info pkg -> lists pkg versions installed
maybe there is already a way to do it, but I could not find it.

it would be nice to have a way to list the versions installed for a given package. it could be as simple as `nimble info pkgname` and it should list all versions installed of that package. I guess it should not be too difficult to implement. It might also report other info (if they are available to nimble) such as source repo, list of binaries that come with the package...

lacking this I always end up looking in `.nimble` folder...

what do you think?
