mttools: 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: I806ef4d6cff03c254dc66dda6e176dab000e0603
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/mttools/+/1682810