This is a reland of 7455b544

Original change's description:
> Instantiate rx::DisplayEGL when device type EGL is selected
>
> Define EGL_PLATFORM_ANGLE_DEVICE_TYPE_EGL_ANGLE that should be
> used to request a driver egl-backed implementation with ANGLE.
>
> Bug: angleproject:4328
> Change-Id: I6871d3a27e2bfc02af9815dcf86ae1cb6524f0cc
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2030038
> Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>
> Reviewed-by: Geoff Lang <geofflang@chromium.org>

Bug: angleproject:4328
Change-Id: I4e997c4fa1b5b59f081436f05bd208303ffe38e9
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2093412Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Commit-Queue: Julien Isorce <julien.isorce@chromium.org>