[graphite] Add runtimeEffectDictionary to KeyContext

During precompile we must accumulate the runtimeEffects in a transient runtimeEffectDictionary so that the SkSL source code will be available when we compile.

Bug: b/261043112
Change-Id: Id2601b2934132ecc3513bd49aa7b3ef3268790ba
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/619038
Reviewed-by: James Godfrey-Kittle <jamesgk@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
11 files changed