Divergent group barriers in Lumen

Intel reported GPU crashes on their hardware caused by divergent group barriers in ScreenProbeConvertToIrradianceCS:

[numthreads(THREADGROUP_SIZE, THREADGROUP_SIZE, 1)]
void ScreenProbeConvertToIrradianceCS(
//...
	if (ScreenProbeIndex < GetNumScreenProbes() && ScreenProbeAtlasCoord.x < ScreenProbeAtlasViewSize.x)
	{
		float SceneDepth = GetScreenProbeDepth(ScreenProbeAtlasCoord);

		if (SceneDepth > 0)
		{
			// ...
			if (all(ProbeTexelCoord < ScreenProbeGatherOctahedronResolution))
			{
				// ...
				GroupMemoryBarrierWithGroupSync();

The crash is difficult to reproduce, but the code does violate the spec, which says that barriers cannot be issued inside divergent branches for the same thread group.

ScreenProbeCompositeTracesWithScatterCS has a similar problem, and Intel's validation code also called out LightGridInjectionCS, FixupBordersAndGenerateMipsCS and ComputeProbeWorldOffsets. We should double-check the sync logic in these as well (at a quick glance, LightGridInjectionCS does your usual bounds check, but then issues a group barrier inside, which is technically wrong).

N/A, see description.