[CrOS Settings] Update OWNERS file for OS settings handlers.

Add all //chrome/browser/resources/settings/chromeos owners as owners of
this directory as well; also update bug component.

Change-Id: I55d54ed10afd418f92d52498c67a6eb5b4b6569b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2065113
Commit-Queue: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Zentaro Kavanagh <zentaro@chromium.org>
Auto-Submit: Kyle Horimoto <khorimoto@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742813}

chrome/browser/ui/webui/settings/chromeos/OWNERS

+file://chrome/browser/resources/settings/chromeos/OWNERS
+
 per-file multidevice_handler*=file://chromeos/components/multidevice/OWNERS
 
-# COMPONENT: UI>Settings
+# COMPONENT: OS>Systems>Settings