add raycast special types (backport to 0.17)

[JMS55]

No description provided.

[robtfm]

@JMS55 can you please see if #119 works - i think it will better support multiple modules using the same special types, so should hopefully allow passing around the special types as well (rayQueryProceed(foo::rq)).

i changed the expected output for the atomics test - now it is outputting clearly invalid source (using an undefined type). but actually, the previous source was also invalid as the type was not the builtin type. it does work with the gpu-based shader test on my machine (though not in CI due to an unrelated error) so i'm comfortable it's still correct.