nir,microsoft: Move scale_fdiv into a common NIR pass

While we're at it, convert to nir_shader_instructions_pass() to get rid
of some boilerplate and get metadata correct.

Reviewed-by: Jesse Natalie <jenatali@microsoft.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15983>

src/compiler/nir/meson.build

@@ -263,6 +263,7 @@ files_libnir = files(
   'nir_range_analysis.h',
   'nir_remove_dead_variables.c',
   'nir_repair_ssa.c',
+  'nir_scale_fdiv.c',
   'nir_schedule.c',
   'nir_schedule.h',
   'nir_search.c',