Recipes module to run adhoc validations.

All the current cirrus checks that include several commands will be
translated to adhoc validations. The current implementation adds scripts
for analyze and fuchsia_precache.

Change-Id: I6cdd2be73c38cc5e729452352dd68bd37a213aa1
Bug: https://github.com/flutter/flutter/issues/62811
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/5120
Commit-Queue: Godofredo Contreras <godofredoc@google.com>
Reviewed-by: Keyong Han <keyonghan@google.com>
Reviewed-by: Tong Wu <wutong@google.com>