The main refactor from this change is to replace statements like this:

  decls, defs, export_defs, _, _, _, _ = get_entry_points(
    apis.EGL, eglxml.all_commands, egl_version_commands, False,
    egl_param_types, cmd_packed_egl_enums, EGL_PACKED_TYPES,
    egl_ep_to_object, TEMPLATE_EGL_ENTRY_POINT_EXPORT)

With statements like this:

  eps = EGLEntryPoints(eglxml, egl_version_commands)

This will make the script easier to maintain and extend.

Bug: angleproject:5653
Change-Id: Ibd0930d45b8629702b7782f43a2d7ebfa4dac9b8
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2705156Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>