Add sample demonstrating VK_KHR_shader_relaxed_extended_instruction

[gpx1000]

Description

Add a sample that shows how to use VK_KHR_shader_relaxed_extended_instruction and tutorial for it.

Fixes #

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[gary-sweet]

I'm not really sure what I'm expecting to see with this sample.

What I'm currently seeing is that I seem to have some seemingly random framebuffers begin displayed, and a bunch of these being printed to the console:

[info] vkQueueSubmit(): pSubmits[0] DebugPrintf:
relaxed-ext-inst demo: gid = 0
[info] vkQueueSubmit(): pSubmits[0] DebugPrintf:
relaxed-ext-inst demo: gid = 0

[Keenuts]

Hello!
I looked at the SPIR-V file in this PR (relaxed_demo.comp.spv) and it seams it has no OpExtInstWithForwardRef instructions.

I don't know if GLSL emits those, but you can have a HLSL shader doing the same thing with the following code:

// RUN: %dxc %s -T cs_6_0 -spirv -fspv-target-env=vulkan1.3 -E main -fspv-debug=vulkan-with-source -O3

class A {
  void foo(uint3 gid) {
    printf("relaxed-ext-inst demo: gid = %u", gid.x);
  }
};

[numthreads(1, 1, 1)]
void main(uint3 gid : SV_DispatchThreadID)
{
  A a;
  a.foo(tid);
}

Here, one OpExtInstWithForwardRefs will be emitted as we have debug info with a class method, which brings a circular dependencies in the debug instructions.

[gpx1000]

Great thanks for the validation of HLSL. I went ahead and switched from GLSL to Slang and validated that it does emit the OpExtInstWithForwardRef instruction. This Sample should now be ready (also merged the latest master and fixed merge conflicts.)