Vulkan: add possibility to build subset of shaders As the number of internal shaders grow, it's helpful in development time to be able to build variations of a specific shader, instead of building everything every time. With this commit, one can do: $ python gen_vk_internal_shaders.py SubString which will result in compilation of shaders whose name matches the glob *SubString*. Bug: angleproject:2958 Change-Id: I3b18d7e32e2ec4317531a7655eb2c6148cea177b Reviewed-on: https://chromium-review.googlesource.com/c/1369285 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>