extract-annotation-query.js is purely about reading a couple of config
settings and is only used by config/config.js, so move it from the util/
dir into a new config/settings.js file.

config/settings.js is going to become a file containing all of the
different functions for reading different config settings. These
functions are imported and used by config/settings.js. For a start, move
extract-annotation-query.js's two functions into settings.js, but later
we'll be adding more functions to this file.

These functions are in a separate settings.js file, rather than just in
the config.js file that uses them, so that they can be unit tested
separately.