[6.x] Use exit code [1] when migration table not found

[jerguslejko]

This PR modifies migrate:status command to return exit code 1 when the migrations table is not found.

Motivation: I plan on using this as a way to see if the database has been migrated at least once. This will be useful when deploying to a new staging environment (when I'm deploying for the first time, I want to run seeders as well).

Thanks for your time!