nir: add generated intrinsic builders
This MR adds generated helpers to create intrinsic instructions, like the existing helpers to create ALU. The parameters for each of the helpers are (in order):
- the
nir_builder *
- the number of destination/intrinsic components, if needed
- the destination bit-size, if needed
- the sources
- the indices, in the order specified in nir_intrinsics.py
Edited by Rhys Perry