Move static feature out of perf features (#13265)
#5577 fixed a bug on macos due to dynamically linking lzma/xz through
static linking. In #7686, this feature was moved to the performance
category.
This PR moves the `xz2/static` back to the general default features,
and, inspired by https://github.com/Homebrew/homebrew-core/pull/222211,
it structures and documents the feature flags cleaner.
We need to take care that this feature does not accidentally disable
features we want.
---------
Co-authored-by: Zanie Blue <contact@zanie.dev>
