Run db commands on test as well as development databases

[timriley]

It's a frustrating experience if users have to remember to run each of their hanami db commands again with -e test after running them on their development database.

To improve this, update a number of commands to automatically re-run on the test database after completing their work on the development database:

• db create
• db drop
• db migrate
• db prepare
• db structure load

The re-run on test will only take place if these commands operate with the development environment. Running the commands in other environments (e.g. production or test) will run on the database in those environments only.

To achieve this "re-run on test" behaviour, at the end of these db commands, we invoke another process to call the relevant hanami db command again, but with the HANAMI_ENV=test environment variable set. For this re-run, all given CLI flags are preserved, but -e and --env are of course stripped.

The reason we have to take this approach is because right now there's no straightforward way to re-boot the Hanami app in a different environment, or stand up the database subsystem itself in a different environment.

I'd like to for us to make one of these possible (certainly the latter feels reasonable) in the future, but to make the user experience as good as possible for 2.2, we're taking a pragmatic approach here.

Resolves #215

[timriley]

This is a bit hacky, but as commented here and in spec/support/hanami_cli_environment.rb, it was necessary because of our current testing approach. Given that I think we'll be able to switch to a cleaner overall approach in the future, I was comfortable with a few hacks like this being employed here.