EGL_CONTEXT_OPENGL_DEBUG is only exposed as of EGL 1.5.
We can also now properly test for no_error extension strings.
Do not require backwards compatible context extensions.

Fixes parts of using EGLWindow to load native EGL drivers.

Bug: angleproject:4596
Change-Id: I4de8f492f265d29f6603ed1b35b123e362699c54
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2176271
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>