FindVulkan: Add targets Vulkan::{Headers,glslangValidator}
Vulkan::Headers target complements existing Vulkan::Vulkan. It is the same except it omits Vulkan library. This way, it allows for applications that loads Vulkan library in run-time, thus the target must not contain Vulkan link-time libraries.
Vulkan::glslangValidator target provides path to the glslangValidator executable. glslangValidator is the tool for converting between shader languages (GLSL, SPIR-V,...). It is very useful in the build process.
Topic-rename: FindVulkan-add-Headers-glslangValidator-targets
Edited by Brad King