Add GraphicsEnv to libgui

This singleton class stores information provided by the framework and
makes it available to EGL/GLES/Vulkan loaders. It will eventually
replace vulkan::LoaderData and possibly the egl blob cache directory
storage.

Bug: 33531483
Change-Id: I40c3952374badabea738a34a51db90bf197979b8
Merged-In: If8b84fd38428f1cc9fcee8ffc25eb90cd87cedb4