Was not outputting correctly. Also print more information like the type
and severity of the message. Moves some stringification code out of
RendererGL into common/utilities.

Bug: angleproject:3630
Change-Id: I029e279764fa4ae5cab8d903bd0ef7d376b7b846
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2067630
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>