Vulkan: Roll VK deps forward Roll VK Headers/Loader/ValidationLayers forward. There's a build improvement as well as many new checks. Added new source file dep, convert_to_renderpass2.cpp, used by core_ validation for added RenderPass2 checks. Also had to move glslang fwd for shader validation layer so updated from confusing upstream branch of glslang that's integrated with shaderc to the independent Khronos glslang repo. Bug: angleproject:2937 Bug: chromium:845519 Change-Id: Ifee911f061dc426404c09499e49c2f029b174d03 Reviewed-on: https://chromium-review.googlesource.com/c/1355508 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Tobin Ehlis <tobine@google.com>