Add partial support for DrawArraysIndirect.
This supports all primitives types except lineloop.

Test:
dEQP.GLES31/functional_draw_indirect_*

Bug: angleproject:3564
Change-Id: I065417a848390070c9f116db6fd3f90c12fb3886
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1811873Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tobin Ehlis <tobine@google.com>
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>