Generalize WGSL polyfilling logic to include arrays.

We now support polyfilling arrays, matrices and arrays of matrices
when native WGSL alignment mismatches std140 alignment.

Change-Id: I06721bb8f9c2e89acc772dd1baaa0861be827033
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/741116
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
16 files changed