Add new sample for VK_EXT_descriptor_heap

[SaschaWillems]

Description

Note: This is still a draft and not yet ready for review.

This PR adds a new sample for the recently released VK_EXT_descriptor_heap extension. It shows off different heap types (resources, samplers).

Fixes #1486

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[ilyachastikov]

In all shader examples you are using descriptor sets (for example layout (set = 1, binding = 0) uniform texture2D textureImage[2];), but according to documentation using descriptor heaps is special case like this: layout(descriptor_heap) uniform texture2D heapTexture2D[];. What the meaning of descritor heaps with using them like descriptor sets? I think this usage example is misleading.

[SaschaWillems]

Please read:

• https://docs.vulkan.org/features/latest/features/proposals/VK_EXT_descriptor_heap.html
• https://docs.vulkan.org/guide/latest/descriptor_heap.html
• https://www.khronos.org/blog/vulkan-introduces-roadmap-2026-and-new-descriptor-heap-extension

There is nothing misleading about this example.