Metal backend pt3: shader translator Implementation of GLSL to MSL translator Bug: angleproject:2634 Change-Id: I66e2374b461548fac46163ea79790a488515e6b0 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1887251 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>