Replaces TCache with (static generation + static/dynamic lookups) of
TType instances, using compile-time template and constexpr magic.

Work started by jmadill here: https://crrev.com/c/776280
With more contributions from jmadill here: https://crrev.com/c/801494

Bug: angleproject:1432
Change-Id: I07181543f8fee4b2606cdd2d0738351e83d4ce57
Reviewed-on: https://chromium-review.googlesource.com/786317
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>