Add more `cartesi-machine.lua` tests and code coverage

[edubart]

Context

The cartesi-machine.lua has many options, many of its prototyping options are not being really tested, because we perform tests more on the cartesi Lua library actually. Occasionally some less used options in the cli are breaking as we refactor things and people have been reporting me. We need to add a test suite for it and ideally use luacov to make sure it's covering the whole file.

Possible solutions

Add tests for every cartesi-machine.lua option, and use luacov to check its coverage. I am willing to do this when I have time to finish #37 which will contain a great overhaul of our Lua tests.