Currently only features that are associated with LocalSettings configuration
can be overriden by query string. Going forward we'd like to expand this to apply
to user preference too.
A generic OverrideableRequirement is created.
The existing OverridableConfigRequirement is refactored to extend OverrideableRequirement
The /UserPreferenceRequirement now extends it
This allows http://localhost:8888/wiki/Spain?vectortypographysurvey=1
to work
Bug: T347900
Change-Id: I11efd6b07192d5d2333f4506e9d87a8c0638d657
