Add recipe-roller as an OWNER of recipe modules.

See https://codereview.chromium.org/2335163004 for why this is needed. The
roller can't land a non-trivial CL with the upstream author's LGTM, because
it's not an OWNER of the recipes in the repo it's rolling into.

Review-Url: https://codereview.chromium.org/2337263002

recipe_modules/OWNERS

+recipe-roller@chromium.org