add json validation to engine

This CL is a follow up of https://flutter-review.googlesource.com/c/recipes/+/6140, to add json validation logic for all engine recipes

Bug: https://github.com/flutter/flutter/issues/64366
Change-Id: I27b4313b8e56084e087f0db7c8fcb2e4d92db8bd
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/6183
Reviewed-by: Tong Wu <wutong@google.com>
Commit-Queue: Keyong Han <keyonghan@google.com>
11 files changed
tree: 65384e0e64a8471920b6c6f81a78747b6bcacf14
  1. infra/
  2. recipe_modules/
  3. recipes/
  4. .gitignore
  5. .style.yapf
  6. OWNERS
  7. recipes.py