Inconsistent directory naming between plonk and honk

[lucasxia01]

For native file structure, we are differentiating between plonk and honk by putting plonk stuff in a plonk/ directory. However, the reverse is true for stdlib - we have a stdlib/recursion/honk/ for honk stdlib stuff but its stdlib/recursion/ for plonk stuff. This inconsistency should be fixed by making it stdlib/recursion/ for honk and stdlib/recursion/plonk for plonk.