Add testing of front end commands

[lerno]

The continuous integration is a bit low on testing command line commands. There are tests for compile and build but there is nothing really principled.

It would be useful to add more such tests, testing everything from passing command line arguments to run, to init.

[bagoette]

I'm looking into adding these tests, and I didn't really find anything that looks like "tests" for these commands other than some GitHub actions that run the compiler and expect a successful exit.

I was thinking about creating a test runner in C (similar to the C3 test suite runner) that would use some of the same testing strategies (ie using #expect, #error, etc in the test files, along with maybe a #command directive)

What do you think about going that route? Or did you have something else in mind?