Autogenerate features Features are now specified in a json file and autogenerated. This is in preparation for more autogeneration to support feature override in tests. This change doesn't yet fix the issues in anglebug.com/6435 and should be a no-op. Bug: angleproject:6435 Change-Id: Icdb63a94dc37b5fef0a356e0fc0b49937e083c8a Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3579941 Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>