Extend eglGetPlatformDisplay to allow feature overrides. Add EGL_FEATURE_OVERRIDES_ENABLED_ANGLE and EGL_FEATURE_OVERRIDES_DISABLED_ANGLE to submit lists of strings naming the features that should be overridden (either enabled or disabled) on display creation. Bug: angleproject:1621 Change-Id: I4bb75c5dbab0e3b701a72069c38f8c60ecfffad2 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1646595 Commit-Queue: Jonah Ryan-Davis <jonahr@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>