Add more team members to OWNERS

These new owners are active members of the client-side team for sync.

We exclude sync/protocol to be more cautious with changes that are
visible over the wire, for backward-compatibility reasons.

Bug: None
Change-Id: Icd5ba4a300701bf993de238b04b3d14f00821bc0
Reviewed-on: https://chromium-review.googlesource.com/1116538Reviewed-by: Tim Schumann <tschumann@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#570704}

components/sync/OWNERS

+jkrcal@chromium.org
+mamir@chromium.org
 mastiz@chromium.org
+melandory@chromium.org
 treib@chromium.org
 tschumann@chromium.org
 

components/sync/protocol/OWNERS

+set noparent
+mastiz@chromium.org
+treib@chromium.org
+tschumann@chromium.org