lint(practice_exercises): prefer `if false` to commenting out (#242)
lint(practice_exercises): prefer `if false` to commenting out (#242)

Let's prefer `if false` over commenting out (or using `when false`).
This ensures that the code still compiles.

This commit also adds a TODO so that we can grep in the codebase for the
disabled checks.

This change also resolves the following compilation hint:
> src/lint/practice_exercises.nim(5, 6) Hint: 'checkFiles' is declared
> but not used [XDeclaredButNotUsed]

exercism/configlet