Floss: Refactor UuidHelper to use static data

UuidHelper needs to create a HashMap every time it's instantiated. This
patch optimizes so that the HashMap and other constant data can be
created just once using lazy_static.

Bug: 196887265
Tag: #floss
Test: ./build.py --target test

Change-Id: I948b88e213e859bd23130a2afe2644d0859c3c79