Add ability to specify path of generated files about containers HOT 2 CLOSED

I started implementing this but realized that the complexity probably isn't worth it. For example, if we support a directory option for generators, we'd need to support this option for every command. A better solution is to have users create the directory they want then cd to that directory and run containers commands there.

mkdir .example
cd .example
containers generate dockerfile
containers list
containers ...
cd .. # finished

I think we could also address targeting a directory for all commands with a .containersrc file as noted in #3.

from containers.

This is a great idea and will provide a lot of flexibility.

from containers.