Less friction when adding environments

[bogdanr]

When adding an environment the user is asked to provide the following:

nimblex:~/CLI# ./hero environments add
Location: sampledata
Name: sampledata
Provider id: sampledata
Error: (400) Invalid Provider id provided: 'sampledata'

It would be much more user friendly if the following happens automatically:

1. Automatically populate the provider ID if only one is configured
2. Present a list of location so users would be able to make the choice much easier.