perf: kernel replace with precise cache

[leodemoura]

Changes:

• We avoid the thread local storage.
• We use a hash map to ensure that cached values are not lost.
• We remove check_system. If this becomes an issue in the future we should precompute the remaining amount of stack space, and use a cheaper check.
• We add a Expr.replaceImpl, and will use it to implement Expr.replace after update-stage0

[leanprover-community-mathlib4-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase de5e07c4d2d0b48dce5cefdb629bc7171134b490 --onto 78c4d6daff4b500a57cf22dfa3f49e00489827c5. (2024-07-20 02:02:56)