[reland] SkMetaData: move from src/ to tools/

Original: https://skia-review.googlesource.com/c/skia/+/227436
Change-Id: Iec326027319f39b0402e1b5c03b327cb26249159
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/227778
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
8 files changed