Move Source/web/scripts/make-file-arrays.py and add namespace option.

I'm about to use this useful script in Source/modules, so a common
denominator location seemed like a good idea. As well, I added a
namespace option as the upcoming use in modules/serviceworkers will be
in WebCore not blink.

R=jochen@chromium.org
BUG=none

Review URL: https://codereview.chromium.org/311343002

git-svn-id: svn://svn.chromium.org/blink/trunk@175575 bbb929c8-8fbe-4397-9dbb-9b2b20218538