tests/EGLProtectedContentTest: Add QueryContext test. Add a test that calls eglQueryContext to query EGL_PROTECTED_CONTENT_EXT. This functionality was implemented by 1fc9b7c6e0e4be4e6ebdc1bd8ccca58fa0fdecfd. Test: angle_end2end_tests --gtest_filter="EGLProtectedContentTest.QueryContext*" Bug: angleproject:6693 Bug: angleproject:6870 Change-Id: I05e6dde96e120ea81e7d4374990e05def100e290 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3358206 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Cody Northrop <cnorthrop@google.com> Commit-Queue: Lubosz Sarnecki <lubosz.sarnecki@collabora.com>