nir: Add and use a new nir_ssa_def_rewrite_uses_src helper

nir: Add and use a new nir_ssa_def_rewrite_uses_src helper

This is currently an alias for nir_ssa_def_rewrite_uses but we move all
the instances which used it to write a non-SSA source to the newly named
helper.

Reviewed-by: Rhys Perry <pendingchaos02@gmail.com>
Acked-by: Alyssa Rosenzweig <alyssa@collabora.com>
Acked-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9383>