Handwritten SPIR-V instruction parse and build code is replaced with
autogenerated functions based on the SPIR-V grammar.

Bug: angleproject:4889
Change-Id: I09d724fd944e79c03fe4eadca3ee3e3ef0b49872
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2644721
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Tim Van Patten <timvp@google.com>