rhi: Add support for resolving depth-stencil

Add setDepthResolveTexture(). Should work similarly to the color
attachments' resolveTexture, but for depth or depth-stencil.

However, this is another fragmented feature.

- D3D11/12:

Not supported. AFAICS multisample resolve (ResolveSubresource) is just
not supported for depth or depth-stencil formats.

- Vulkan:

Not supported with Vulkan 1.0.

Supported with Vulkan 1.1 and the two extensions.
(VK_KHR_depth_stencil_resolve which in turn requires
VK_KHR_create_renderpass2 since the 1.0 structs are not extensible, so
now need to use VkRenderPassCreateInfo2 and all the '2' structs)

In Vulkan 1.2 the above are in core, without the KHR suffix, but we
cannot just use that because our main target, the Quest 3 (Android) is
Vulkan 1.1.  So 1.2 and up is ignored for now and we always look for
the 1.1 KHR extensions.

The depth resolve filter is forced for SAMPLE_0. AVG seems to be
supported on desktop (NVIDIA) at least, but that's not guaranteed, so
would need physical device support checks. On the Quest 3 it does not
seem to be supported. And in any case, other APIs such as Metal do not
have an AVG filter mode at all, so just use SAMPLE_0 always.

- OpenGL (not ES):

Should work, both when the multisample data is a renderbuffer and a
texture. Relies on glBlitFramebuffer with filter NEAREST. What it does
internally, with regards to the depth/stencil resolve mode, is not under
our control.

- OpenGL ES:

Should work when the multisample buffer is a texture. But it will not
work when a multisample renderbuffer (setDepthStencilBuffer, not
setDepthTexture) is used because the GLES-only multisample extensions
(GL_EXT_multisampled_render_to_texture,
GL_OVR_multiview_multisampled_render_to_texture, which we prefer over
the explicit resolve-based approach) work with textures only.

- Metal:

Should work.

Task-number: QTBUG-122292
Change-Id: Ifa7ca5e1be78227bd6bd7546dde3a62f7fdbc95e
Reviewed-by: Andy Nichols <[email protected]>

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