cmd_fsck: use access_local(), remove dead AnyView::load()

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>

src/main.rs

@@ -460,7 +460,7 @@ impl Run for AdminCmd {
             Self::Init          => cli::admin::cmd_init().await,
             Self::Health        => cli::admin::cmd_health().await,
             Self::Topology      => cli::admin::cmd_topology().await,
-            Self::Fsck          => cli::admin::cmd_fsck(),
+            Self::Fsck          => cli::admin::cmd_fsck().await,
             Self::Dedup { apply } => cli::admin::cmd_dedup(apply).await,
             Self::DailyCheck    => cli::admin::cmd_daily_check().await,
             Self::Import { files } => cli::admin::cmd_import(&files).await,