move Builder/Program dump()

This is test-only code only used by SkVMTest.cpp,
so it can live there.  This cuts the dependency
of SkVM on SkStream and co.

Change-Id: I7695e527b2d16e4485f8c5f4cd39bb8300e9221d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/225321
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
5 files changed