Add `UnneededCapitalW` cop

Add new cop `UnneededCapitalW` which detects usage of %W when
interpolation is not needed and %w would so.
[Refactor] Extract module OptionsHelp from Options

Put all help texts in one place.
[Refactor] Move methods from ConfigLoader to Config

Takes care of the code smell "Feature Envy" in ConfigLoader and
makes it smaller. Two birds with one stone.