[clang-tidy] Store all ranges in clang::tooling::Diagnostic

Summary: Instead of dropping all the ranges associated with a Diagnostic when
converting them to a ClangTidy error, instead attach them to the ClangTidyError,
so they can be consumed by other APIs.

Patch by Joe Turner <joturner@google.com>.
Differential Revision: https://reviews.llvm.org/D69782