Shuffle SkSL sources around so compiler and bytecode can be used w/o GPU

Change-Id: I7236a30040ab532086e68d6e9de2898dd7acaa32
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/221098
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
8 files changed