Fixes linear filtering when using vkCmdBlitImage(), useful for mipmap generation. Move MVKCmdBlitImage sampler definition to shader as a constexpr sampler, and ensure mip_filter and filter are set correctly. Add MVKRPSKeyBlitImg::srcFilter. Include MVKCommonEnvironment.h in MVKLogging.h. Update MoltenVK version to 1.0.39.