This PR introduces new HLSL resource type attribute
`[[hlsl::raw_buffer]]`. Presence of this attribute on a resource handle
means that the resource does not require typed element access. The
attribute will be used on resource handles that represent buffers like
`StructuredBuffer` or `ByteAddressBuffer` and in DXIL it will be
translated to target extension type `dx.RawBuffer`.
Fixes#107907