OGM-600 Establishing ForwardingGridDialect base class to facilitate the ...

...addition of further dialect facets and chaining them
Hey, I've pushed two more commits which you should like better :) There is now a generic method

    <T extends GridDialect> T getDialectFacetOrNull(GridDialect gridDialect, Class<T> facetType)

which works for all facet interfaces potentially added in the future. I agree it's better, thanks for pushing me into the right direction :)