Add support for matrix-scalar operations in SPIR-V.

Multiplication is handled just as before. Ops other than multiplication
are handled by splatting the scalar into a matrix, then performing the
op as a componentwise matrix-op-matrix binary expression.

Change-Id: I654715c45bf5c91b8e9660fdf1c1c6d6818b621a
Bug: skia:11985
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/408637
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
7 files changed