xrt: Add separate build config for OpenGL ES

CMakeLists.txt

meson.build

meson_options.txt

src/xrt/auxiliary/CMakeLists.txt

src/xrt/auxiliary/meson.build

src/xrt/auxiliary/ogl/ogles_api.c

src/xrt/auxiliary/ogl/ogles_api.h

src/xrt/compositor/CMakeLists.txt

src/xrt/compositor/client/comp_gl_client.c

src/xrt/compositor/meson.build

src/xrt/include/xrt/meson.build

src/xrt/include/xrt/xrt_config_have.h.cmake_in

src/xrt/include/xrt/xrt_openxr_includes.h

src/xrt/state_trackers/oxr/CMakeLists.txt

src/xrt/state_trackers/oxr/meson.build

src/xrt/state_trackers/oxr/oxr_objects.h