This CL moves all of the EGLDisplay configuration into an EGL platform
struct. Consolidating display configuration in the struct allows us to
move configuration out of the test constructor. Then when we filter
test configs we don't need to wait for the individual test setup.

Bug: angleproject:3393
Change-Id: I5bd06dcdc9f2867ebc43c1d4984077ada35cafc8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1574674
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>