Move metadata in OWNERS files to DIR_METADATA files

Bug: 1113033
Change-Id: I88c7a659555b3314eddb018a29e025eb5a43690c
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/40302
Auto-Submit: Edward Lesmes <ehmaldonado@google.com>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
diff --git a/DIR_METADATA b/DIR_METADATA
new file mode 100644
index 0000000..0ca8187
--- /dev/null
+++ b/DIR_METADATA
@@ -0,0 +1,3 @@
+monorail {
+  component: "Internals>GPU>Dawn"
+}