nir: add transform feedback info into nir_intrinsic_store_output
This will allow compaction of transform feedback varyings because they
are no longer tied to varying slots with this information.
It will also make transform feedback info available to all NIR passes
after IO is lowered. It's meant to replace pipe_stream_output_info.
Other intrinsics are not used with transform feedback.
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14388>