Add DIR_METADATA

BUG=b:233872079

Change-Id: I280592b620d63b7bd8040c4c96b4a638a0ef8d5a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/common_bazel/+/5500679
Reviewed-by: Shik Chen <shik@chromium.org>
Tested-by: Li-Yu Yu <aaronyu@google.com>