Add skia tools util to set deserial procs for SKP decoding.

This specifically sets default values for decoding images and typefaces.
We had many of our tools missing one or both of these procs which was
causing us not to render the full SKPs. This makes sure all our tools
are deserializing skps correctly and has one shared place in code to
set these default values.

Change-Id: I242b9efead3e9fba349664f3c78c0df9f877ba44
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1141777
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
Auto-Submit: Greg Daniel <egdaniel@google.com>