Adds tests for quantizeToF16 and related infrastructure
Implements f16 support in the framework as needed for quantizeToF16
Adds petamoriken/float16 v3.6.6
Upstream https://github.com/petamoriken/float16
This adds native-like float16 support for implementing quantizeToF16
tests, and future f16 work.
Fixes#1812Fixes#1200
