rootdev: Add OWNERS file

This CL is populating OWNERS file based on the candidates in the Chrome OS OWNERS status sheet.

BUG=b:132095048
TEST=None

Change-Id: I91afc597bb60e32b008f13780868c4d9007bc058
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/rootdev/+/1682217