Replace wdi_property_store.wd_properties with calls to the constraint check api

[stuppie]

The defaults in wdi_property_store.wd_properties are not very generic and cause issues with running a local wikibase (it must be cleared).
Consider removing this and using the Constraint system instead.

[stuppie]

Proposal:

On wikidata, the default core IDs will be the properties with a distinct values constraint
(select ?p where {?p wdt:P2302 wd:Q21502410} (run))

On a wikibase, we need some way of getting the property constraint qid and pids, so this will be empty by default. There was talk at the workshop of making a standard "config" file for a wikibase instance that would list things like these IDs. WDI could use this config file to retrieve these, as well as other things it may need like mapping relation type QIDs
See: https://phabricator.wikimedia.org/T197588

[stuppie]

Done here: 1c298a7
Will merge once I fix some bots...