[Paint Preview] Add myself to OWNERS

Add ckitagawa@chromium.org to OWNERS of components/paint_preview

Change-Id: I6ecdd1d6d7ef98ffba95d1536c2799b10ee35f05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1853127
Auto-Submit: Calder Kitagawa <ckitagawa@chromium.org>
Reviewed-by: Mehran Mahmoudi <mahmoudi@chromium.org>
Commit-Queue: Calder Kitagawa <ckitagawa@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704684}

components/paint_preview/OWNERS

+ckitagawa@chromium.org
 mahmoudi@chromium.org
 vollick@chromium.org
 yfriedman@chromium.org