refactor: expose in-memory and disk cache API (#1096)

Author: MrCroxx

foyer/src/hybrid/cache.rs

@@ -526,6 +526,11 @@ where
         &self.inner.memory
     }
 
+    /// Access the disk cache.
+    pub fn storage(&self) -> &Store<K, V, S, HybridCacheProperties> {
+        &self.inner.storage
+    }
+
     /// Enable tracing.
     #[cfg(feature = "tracing")]
     pub fn enable_tracing(&self) {
@@ -847,10 +852,6 @@ where
         self.inner.storage.is_enabled()
     }
 
-    pub(crate) fn storage(&self) -> &Store<K, V, S, HybridCacheProperties> {
-        &self.inner.storage
-    }
-
     pub(crate) fn metrics(&self) -> &Arc<Metrics> {
         &self.inner.metrics
     }