Numerous rule changes to support validating Tessellation Control and
Evaluation shaders. New per-patch inputs and output variable support.
Includes a new traverser step that validates barrier function calls.

Functionality changes upcoming in http://crrev.com/c/2568234

Bug: angleproject:3572
Change-Id: If8da1c21d30efa12c60ed0d6c3f8cf0b27e4c86f
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2633936
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Mohan Maiya <m.maiya@samsung.com>