This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.
I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
This allows removing the clangAST dependency from libclangToolingCore and
therefore allows clang-format to be built without depending on clangAST.
Before 1166 files had to be compiled for clang-format, now only 796.
Reviewed By: bkramer
Differential Revision: https://reviews.llvm.org/D89708