bug: Make --test argument also check unittests

[wawel37]

Currenctly when we put the

pub fn f1() -> u32 {
  1
}

#[cfg(test)]
mod tests {
    use hello_world::f1;
    #[test]
    fn invisible_to_linter() {
        let x = true;
        if false == x {
            println!("x is false");
        }
        assert_eq!(1, f1());
    }
}

inside the lib.cairo, linter won't catch the false == x problem inside the invisible_to_linter.

When we create /tests/test1.cairo integration test, linter catches it with no problem.