vulkan/swapchain: update scoring for surface formats
Don't filter formats and instead score them correctly to pick the best one. Allowing fallback if something is not available for given transfer.
It's on user to decide what transfer format works for them and if platform supports only 8-bit PQ than it's on them. Still libplacebo will trie it's best to pick surface suitable for transfer.
Also no longer select 16-bit UNROM for SDR, this was regressed by dc79ca11. Because only SFLOAT formats were filtered out.