Allow arguments for _count fields

[f8k8]

Fixes #322

[AhmedElywa]

This one will need to update all generators, not only the SDL.
If you can do it, thank you.
If not, I will do it

[f8k8]

I've only looked at the SDL one as that's the one we use. I can try to find time to look at the others but it might not be for a while.

[f8k8]

I've had another look at this and I think the change already applies to all generators, as it's in the packages/generator/src/Generators.ts and packages/plugins/src/select.ts files, and not anything in the specific SDL generator. The snapshots updated are the SDL one and the graphql-modules one. The Nexus snapshot hasn't changed, but looking at it I think the nexus one might already have the arguments for counts, though I'm not sure as I don't really know anything about Nexus.