spirv: Implement NoSignedWrap and NoUnsignedWrap decorations

spirv: Implement NoSignedWrap and NoUnsignedWrap decorations

When handling the specified ALU operations, check for the decorations
and set nir_alu_instr no_signed_wrap and no_unsigned_wrap flags accordingly.

v2: Add a glsl_base_type_is_unsigned_integer() helper.  (Karol)

v3: Rename helper to glsl_base_type_is_uint().

v4: Use two flags, so we don't need the helper anymore.  (Connor)

v5: Pass alu directly to handle function.  (Jason)

Reviewed-by: Karol Herbst <kherbst@redhat.com> [v3]
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>