Fully remove typecache

[tmcw]

The typecache was no longer used as of #1023 but we never fully removed it. So, an unnecessary Map was still being created per call to parse or safeParse. This removes that call.

Benchmarks: https://observablehq.com/d/b4b367792308cedb

Since this is a performance bump that just affects the top-level method, the impact on microtests is dramatic - like 20%+. For example, this code benefits dramatically:

const str = z.string();
str.parse('foo');

There probably aren't that many people who have such small zod schemas in prod, but nevertheless… it was wasted memory and time and now it isn't.

There's still a very large gap between zod & myzod for primitives which I've having a tough time bridging, still working on that.