Add exercises with type-tests

[SleeplessByte]

• Add a mini test runner to each exercise that determine if
  • it should run tsc (right now always yes)
  • it should run tstyche (only if there are type tests)
  • it should run jest (only if there are implementation tests)

Additionally implements the first concept exercise.

[SleeplessByte]

Should merge this first (with [no-important-files-changed] if necessary) before more work is done on this track so we can keep the changes unrelated to the concepts out of those PRs.

[SleeplessByte]

@ErikSchierboom setting the concept exercise to beta should work? Or will that make the concept tree show on the site? I don't want that (yet) as I am writing (a lot) of exercises.

[ErikSchierboom]

beta exercises are available to anyone, wip only to maintainers:

def enabled_exercises(exercises)
    status = %i[active beta]
    status << :wip if maintainer?

[SleeplessByte]

Will change!