ListObjects Metadata Caching (#10648)

Design: https://gist.github.com/klauspost/025c09b48ed4a1293c917cecfabdf21c

Gist of improvements:

* Cross-server caching and listing will use the same data across servers and requests.
* Lists can be arbitrarily resumed at a constant speed.
* Metadata for all files scanned is stored for streaming retrieval.
* The existing bloom filters controlled by the crawler is used for validating caches.
* Concurrent requests for the same data (or parts of it) will not spawn additional walkers.
* Listing a subdirectory of an existing recursive cache will use the cache.
* All listing operations are fully streamable so the number of objects in a bucket no 
  longer dictates the amount of memory.
* Listings can be handled by any server within the cluster.
* Caches are cleaned up when out of date or superseded by a more recent one.

cmd/xl-storage_windows_test.go

@@ -68,7 +68,7 @@ func TestUNCPaths(t *testing.T) {
 			} else if err == nil && !test.pass {
 				t.Error(err)
 			}
-			fs.DeleteFile(context.Background(), "voldir", test.objName)
+			fs.Delete(context.Background(), "voldir", test.objName, false)
 		})
 	}
 }