Add a builder recipe for flutter engine builds.

This is one of the first steps to split engine recipes in smaller tasks
with a goal of running all of them in less than 30 mins.

Change-Id: I2cfffc7267ad5ca6cba96603dd994531ed848037
Bug: https://github.com/flutter/flutter/issues/81855
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/13740
Reviewed-by: Zach Anderson <zra@google.com>
Reviewed-by: Yegor Jbanov <yjbanov@google.com>
Commit-Queue: Godofredo Contreras <godofredoc@google.com>