DevTools: Extract frontend modules "common", "sdk", "ui", "components" into their directories

R=pfeldman@chromium.org, pfeldman

Review URL: https://codereview.chromium.org/246933009

git-svn-id: svn://svn.chromium.org/blink/trunk@172493 bbb929c8-8fbe-4397-9dbb-9b2b20218538