Emit OVR_multiview2 on ESSL/GLSL outputs. Add ARB_shader_viewport_layer_array support to SH_SELECT_VIEW_IN_NV_GLSL_VERTEX_SHADER. Bug: angleproject:3404 Change-Id: Ia89517d0cc92400ce47c9118e8c1abf8285aec41 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1585452 Reviewed-by: Jamie Madill <jmadill@chromium.org>