Revert "SkMetaData: move from src/ to tools/"

This reverts commit 9d844d8ce5a29130686d1e2f3d612b180cef5f0b.

Reason for revert: breaking google3

Original change's description:
> SkMetaData: move from src/ to tools/
> 
> Change-Id: If581c8ceeaa76985535cb7b6772742f0011cfe8e
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/227436
> Commit-Queue: Hal Canary <halcanary@google.com>
> Commit-Queue: Ben Wagner <bungeman@google.com>
> Auto-Submit: Hal Canary <halcanary@google.com>
> Reviewed-by: Ben Wagner <bungeman@google.com>

TBR=halcanary@google.com,bungeman@google.com

Change-Id: Ifadad46f0663b743d3e57bb6317707f2a2fac07d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/227636
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
7 files changed