Merge TableGen files used for clang options

Summary:
Putting all the options in the same file is needed so they can be
ordered based on the dependencies between them.

Reviewers: Bigcheese, jdoerfert

Subscribers: dexonsmith, sstefan1, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82574

Author: daniel-grumberg