Handle duplicate names

[Fauntleroy]

You can't have two emoji with the same name, so what do we do with conflicts?

• Warn the user about the conflict and ask for a manual rename?
• Automatically iterate the emoji name with a number?

[vlad-roid]

I suggest the 2nd option with the automatic numbering, much more convenient

[CJGlitter]

Almost done with a solution for this on my fork/branch add-name-taken-retry-logic. Just trying to figure out how to test the solution with the npm dependency issues blocking me.

It will append -# to any duplicated emoji names and increment the number to keep retrying.