moved SkSL Swizzle data into IRNode

Change-Id: Idb10db5cc4fff4f10ce84c5ae021e4c0e7bfc49b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/325662
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
15 files changed