add rsm result

[docteurklein]

Allows the pagination of native queries, by passing a closure to generate the count query.

Requires to pass a DBAL\QueryBuilder instance.

[beberlei]

@docteurklein I think this is a bit too complicated to be really useful as a generic implementation or?

[docteurklein]

I agree it it qute complicated, however it is a generic implementation, that will work with complex use cases where RSM is mandatory.

Currently I had to use RSM because the DQL didn't allow me to ORDER BY stuff IS NULL DESC.
Maybe I could add a sql walker to handle my case, but still, this adapter has its place IMHO.

PS: sorry for the delay.