RenderBuffers are now created with VK_KHR_image_format_list
extension support enabled. We only enable those tests where
the EGL image's source is a RenderBuffer but not those tests
where the EGL image's target is a RenderBuffer. There are some
corner cases related to glReadPixles that need to be resolved
to unblock those tests.

Bug: angleproject:3756
Bug: angleproject:5281
Test: ImageTest.SourceRenderbuffer*Vulkan
Change-Id: I643a9d74d14473cc7df59fa6e25acab7d1c9aad1
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2528475Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>