Deprecate the WellPtr -> shared_ptr aliases. The Schedule object is the
sole owner of these objects, and shared_ptr in the interfaces hid that.
The interfaces still relies on pointers to pass Wells around for now,
in order to (mostly) preserve source compability.
Occasionally the SUMMARY section requests wells or groups that aren't
defined in the Deck. Ignore these names (which would typically crash
downstream) and carry on.
This object turns out to be the actual configuration object, not a
mediator state to obtain a configuration. It is therefore renamed to
reflect intent and behaviour.
