Convert cmd_fsck to async and use access_local() for the cached store.
Still uses Store::load_from_logs() for fresh comparison.
Remove unused AnyView::load() method - was never called.
Remaining Store::load() calls are all internal caching infrastructure:
- persist.rs cached() for CACHED_STORE
- mod.rs access() fallback for STORE_ACCESS
Co-Authored-By: Proof of Concept <poc@bcachefs.org>