Make dfried OWNER of layouts

Was originally a bunch of per-file but I've written half the folder at
this point, so...

Change-Id: I0b2c5e4315a93133ca4294d831503ab1a1bb3e36
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1815666Reviewed-by: Robert Liao <robliao@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/master@{#698557}

ui/views/layout/OWNERS

-per-file flex_layout*=dfried@chromium.org
-per-file layout_manager_base*=dfried@chromium.org
+dfried@chromium.org