Add support for 565 to Windows. Also includes code that verifies
generated configs can actually be supported by Vulkan.
Test:
--use-angle=swiftshader --deqp-gl-config-name=rgb565d0s0ms0 --gtest_filter=dEQP.GLES3/functional_fragment_ops_interaction_basic_shader_80

Bug: angleproject:4016
Change-Id: Idcfd4dd368c4a30ef177aa89e1035d2f00570c99
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1885378Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>