In preparation for more source-side configuration. Also adds a presubmit
check and some empty files to enable the presubmit to function.

Bug: angleproject:5114
Change-Id: Id9a0cbe1e78949720be39c65efab73c1345d4f39
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2819942Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>