This also creates a common code path for all framebuffer
completeness errors (FramebufferStatus::Incomplete) which
helps for adding a debug breakpoint.

Bug: angleproject:5949
Change-Id: Ib102dbf86e020777e56c6dc6b78dda8ebdba2127
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2888110
Commit-Queue: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>