Vulkan video filters: deinterlace, adjust and others

After video decoding in VLC it might be that the user wants to use a specific filter like deinterlace and/or adjust and/or other filters that run on the GPU before the frame gets displayed. Vulkan branch now misses filters support and many GPU-accelerated filters in VLC that some of them currently existed in OpenGL pipeline (deinterlace) not yet available for the Vulkan pipeline. And other filters are not implemented in Vulkan and OpenGL (adjust). This project will introduce the Vulkan-based filtering abstraction and implement some filters such as deinterlace and adjust-style filters (brightness, contrast, saturation, gamma) using Vulkan shaders.