This adds two final auto-generated files for the EGL and EXT extension
entry points. It adds a new data file that stores a mapping between
object types and entry points for associating labeled objects with
certain methods. When we generate errors we record the associated
object in the debug message output.

This places the remainder of the hand-written code in "stub" files.
Going forward the work for implementing new extension entry points
for EGL will be to update the registry XML files and then implement
the corresponding stub methods. Event logging, parameter packing,
and validation are all handled by the auto-generated code.

Bug: angleproject:2621
Change-Id: I28153432802c37b929ff2ea1e1a3e3ce9de91605
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2562680
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>