Stop Vulkan generating validation error in build acceleration structures

[Vecvec]

Connections
fixes #6278

Description
This stops vulkan validation layers giving an error when index buffer is not specified, also updates ray-traced triangle to be configurable whether to use an index buffer.

Testing
run raytraced triangle without argument index_buffer, before:

    Rgba8Unorm,
    Rgba8UnormSrgb,
]
[2024-09-16T05:12:41Z ERROR wgpu_hal::vulkan::instance] VALIDATION [VUID-vkCmdBuildAccelerationStructuresKHR-pInfos-03806 (0x76173dcc)]
        Validation Error: [ VUID-vkCmdBuildAccelerationStructuresKHR-pInfos-03806 ] Object 0: handle = 0x1be9895ffa0, name = init, type = VK_OBJECT_TYPE_COMMAND_BUFFER; | MessageID = 0x76173dcc | vkCmdBuildAccelerationStructuresKHR(): pInfos[0].pGeometries[0].
geometry.triangles.indexData.deviceAddress (0x0) is not an address belonging to an existing buffer. pInfos[0].pGeometries[0].geometry.triangles.indexType is VK_INDEX_TYPE_UINT16. The Vulkan spec states: For any element of pInfos[i].pGeometries or pInfos[i].ppG
eometries with a geometryType of VK_GEOMETRY_TYPE_TRIANGLES_KHR, if geometry.triangles.indexType is not VK_INDEX_TYPE_NONE_KHR, geometry.triangles.indexData.deviceAddress must be a valid device address obtained from vkGetBufferDeviceAddress (https://www.khronos.org/registry/vulkan/specs/1.3-extensions/html/vkspec.html#VUID-vkCmdBuildAccelerationStructuresKHR-pInfos-03806)
[2024-09-16T05:12:41Z ERROR wgpu_hal::vulkan::instance]         objects: (type: COMMAND_BUFFER, hndl: 0x1be9895ffa0, name: init)

after:

 Bgra8UnormSrgb,
    Rgba8Unorm,
    Rgba8UnormSrgb,
]

Process finished with exit code 0

Checklist

• Run cargo fmt.
• Run cargo clippy. If applicable, add:
  • [] --target wasm32-unknown-unknown N/a
  • [] --target wasm32-unknown-emscripten N/a
• Run cargo xtask test to run tests.
• Add change to CHANGELOG.md. See simple instructions inside file.