Vulkan: Use user names directly in SPIR-V ... instead of prefixing them with _u. The transformer no longer relies on debug info, which means SPIR-V names can be completely arbitrary. There is no risk of collision with ANGLE internal names because it doesn't matter for SPIR-V, and SPIR-V Cross is able to handle duplicate names. This change makes the output of SPIR-V Cross on generated shaders more readable as it's not cluttered with _u before every name. Bug: angleproject:7220 Change-Id: If46f7c82f908b0d65f8be49e297384ab659369e8 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4615237 Reviewed-by: Yuxin Hu <yuxinhu@google.com> Reviewed-by: Roman Lavrov <romanl@google.com> Commit-Queue: Roman Lavrov <romanl@google.com> Auto-Submit: Shahbaz Youssefi <syoussefi@chromium.org>