Feat: support external commands

[samuelroland]

Complex execution of binaries like in SYE: sh.elf with a non supported build command like cmake cmake . -Bbuild && cmake --build build/ can benefit from this.

Checking output of an external command like tree to validate a structure of folder is another benefit that could help train little tools like Yazi, Gitui and others.

TODOs

• Create branch feat-external-commands
• Create basic exos for testing with multiplateform commands like ls, echo, including shells specific like $() and | to make sure it is ran in the shell.
• Define data structures for this new test type command
• Support cmd (command ran in a shell), expected (expected output): ex. test = { type = 'command', cmd = 'fd -e png | wc -l', expected = "1" }
• Support wd (working directory), swd (solution working directory): test = { type = 'command', cmd = 'tree d e f', wd = 'train', swd = 'sol' }. The output must match between execution of cmd inside wd and the execution inside swd.
• Tests failing checks and working checks
• Fail parsing if swd and expected are provided.
• Mandatory fields cmd, all other optional.

cc: @AndreCostaaa what do you think about these data structures and how this is going to be parsed by serde ?

Help

• Use current_dir() on a process

[AndreCostaaa]

Parsing should be ok
We can easily convert
test = { type = 'command', cmd = 'tree d e f', wd = 'train', swd = 'sol' }
to
test = { type = 'command', cmd = 'fd -e png | wc -l', expected = "1" }

By actually running the command and collecting the output on startup for instance

This could be a good way to simplify and avoid running multiple times the same command if there are multiple iterations of the exercise