[clang] Store code completion token range in preprocessor.

[clang] Store code completion token range in preprocessor.

Summary:
This change is to support a new fature in clangd, tests will be send toclang-tools-extra with that change.

Unittests are included in: https://reviews.llvm.org/D50449

Reviewers: ilya-biryukov

Reviewed By: ilya-biryukov

Subscribers: ioeric, MaskRay, jkorous, arphaman, cfe-commits

Differential Revision: https://reviews.llvm.org/D50443

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@339540 91177308-0d34-0410-b5e6-96231b3b80d8