be able to give a short name for a pack-repo

[michelleN]

Currently, output for draft pack-repo list looks like this:

$ draft pack-repo list
github.com/Azure/draft
github.com/michelleN/draft-packs

It'd be nice for us to be able to give a short name to reference the pack-repo via a flag. If the flag is not given, we can create a default name. The default could look like this michelleN-draft-packs or Azure-draft. It would be the concatenation of the repo org and name replacing the / with a hyphen -

Example experience:

$ draft pack-repo add https://github.com/michelleN/draft-packs -n michelle
Installing pack repo "michelle" from https://github.com/Azure/draft
Installed pack repository "michelle" from github.com/Azure/draft

$ draft pack-repo list
Name                 Location
Azure-draft          github.com/Azure/draft
michelleN            github.com/michelleN/draft-packs

related to #465

[bacongobbler]

What if we made the location configurable? There's a similar thread going on for GoFish in https://github.com/fishworks/gofish/issues/66 in case you draw some ideas from there :)