Move the supporting widgets for the contact maps feature alongside
EABContactDisplay.  Removing them from libeutil helps isolate our usage
of libchamplain so it's not imposed on the entire application, and even
3rd party software.  That libchamplain is an optional dependency only
further complicates the matter.

Ideally I'd like to somehow isolate this feature in an extension module,
but we currently lack sufficient hooks for such an extension.  So this
arrangement will have to suffice for now.