vulkan scaled vertex formats

[Graine25]

This PR adds RenderFormat entries and Vulkan mappings for R8G8B8A8_USCALED, R16G16_SSCALED, and R16G16B16A16_SSCALED. re:Blue needs these formats when running through MVK so the vertex data can reach floating-point shader inputs without causing mismatches during pipeline creation.

• R8G8B8A8_USCALED: Unsigned quads become unnormalized floating-point attributes.
• R16G16_SSCALED: Signed pairs become unnormalized floating-point attributes.
• R16G16B16A16_SSCALED: Signed quads become unnormalized floating-point attributes.

[DarioSamo]

Explained over Discord already, but we want to avoid data formats that will fail on other backends, and in this case, there's no direct equivalent for these formats in D3D12. We could use UINT and SINT directly as the DXGI type, but then it could lead to a potential mismatch of what the shader declares and the format that is used. I'm currently unsure whether that operation is guaranteed to work correctly under DXIL: the input being declared as float but the format being an integer.