Introduce Image2DBufferSpecification for Image ViewType abstractation

[JeanPhilippeKernel]

As today, we have the option to create flat texture 2D or a cubemap (composition of 6 texture 2D).
the implementation of creating a cubemap has been hard-coded based on a fixed image format: VK_FORMAT_R32G32B32A32_SFLOAT which is handling by the Image2DBuffer abstraction

To ease the creation of whether a flat 2D image buffer or cubemap buffer, we want to introduce Image2DBufferSpecification which will take care of the user config and drive the process of creation.

The specification should allow the caller to tell whether the buffer is for flat 2d image or cubemap