Created by: kexinzhao

Fix #10315 (closed)

This pr does the following things:

1. Make float16 transpiler an independent component.
2. update the benchmark result using the latest float16 transpiler.
3. add float16 demo code float16_inference_demo.py and add run_float16_demo.sh to run it to get the benchmark results.
4. move the transpiler, benchmark result, and demo code into contrib/float16 folder.
5. add float16 report summarizing the work