Move interpreter disassemble to out-of-line member of ByteCode

Now it returns a string (rather than just calling printf).

Adds GUI view of particle effect byte code (for fun), and fixes the
unit tests that called ByteCodeFunction::disassemble, which wasn't
doing anything.

Change-Id: Ide3fd933cf14832feae7ff9e0fdc1ae8f24a28d4
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/273878
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
6 files changed