Makes the behavoral change of #13263 without the underlying refactor.
Hopefully this clearly safe from a perf and GC perspective, and will
make it easier to benchmark #13263.
This is a big step documenting the store layer on its own, separately from the evaluator (and `builtins.derivation`).
Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
