Adds support for translating gl_DrawID for implementation of
GL_ANGLE_multi_draw.

Currently the change only supports and allows emulation of the
draw id using a uniform variable named `gl_DrawID`. This uniform is
mapped in the translated shader to a hashed name that does not
use the gl_ namespace

Bug: chromium:890539

Change-Id: I08a246ca911e88e733ccdf22f1ed69dcae948e05
Reviewed-on: https://chromium-review.googlesource.com/c/1271957
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>