st/dri: Set next in template instead of after creation. (v2)

st/dri: Set next in template instead of after creation. (v2)

This should prevent horrors like Iris has with the delayed calls
to iris_resource_finish_aux_import just because info is not
available at allocation time.

AFAICT all drivers just copy the template except radeonsi/r600
which reset the next pointer.

AFAICT there is also no other place we get a state tracker setting
next ptrs on a resource.

v2: Updated Gallium docs.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3792>