Compute shader inputs were not being tracked in the Shader or Program
states, causing program interface queries to fail. This change treats
compute shader inputs (all built-ins) as Attributes and pipes them
through from the Compiler to the Program to enable input queries. While
compute shader inputs are not technically attributes (or varyings),
the ANGLE code understands and handles attributes and a program
can never have both a vertex and compute shader, so there can't be any
conflicts.

The naming of these variable lists should probabaly be revisited at some
point to better handle these different use-cases.

Bug: angleproject:3596
Test: dEQP-GLES31.functional.program_interface_query.program_input.resource_list.compute.empty
Change-Id: Ie52cd59041868cfdb5d3d759bb4ec53c8d5b38d5
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1919557Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Tim Van Patten <timvp@google.com>