PIM-3224 : introduce a PQB factory to illustrate product query API
revamping
PIM-3224 : remove the CatalogContext from the ProductQueryBuilder

Conflicts:
	CHANGELOG.md
PIM-3224 : investigate on decoupling grid and pqb through filter utility
PIM-3224 : update the product filters to use the utility class and (avoid
to manipulate qb)
PIM-3224 : update product datagrid sorters to avoid to manipulate qb
PIM-3224 : remove createProductQueryBuilder from repository and use
factory
PIM-3224 : update product query factory and product datasource
PIM-3224 : add specific datasource adapters for product datasource and
update related resolver
PIM-3224 : update default call in product query factory
PIM-3224 : fix ORM issues with products grid (variant group and
association)
PIM-3224 : inject PQB class in the factory
Merge pull request #1620 from akeneo/PIM-3224

PIM-3224 : ProductQueryFactory, new instance for PQB, update grid filters/sorters