Support for `CONSOLE_OFF=` and `CONSOLE_ALL=`

[fnordfish]

Description

See #21

$ CONSOLE_LEVEL=error CONSOLE_ALL=Focus::Class CONSOLE_OFF=Not::Interested::Class ./machine

Types of Changes

• New feature.

Testing

• [x] I added tests for my changes.
• [x] I tested my changes locally.
• [ ] I tested my changes in staging.
• [ ] I tested my changes in production.

[ioquatix]

This looks good to me.