[clang-apply-replacements] Convert tooling::Replacements to tooling::AtomicChange...

[clang-apply-replacements] Convert tooling::Replacements to tooling::AtomicChange for conflict resolving of changes, code cleanup, and code formatting.

Summary:
By converting Replacements by AtomicChange, clang-apply-replacements is able like clang-tidy to automatically cleanup and format changes.
This should permits to close this ticket: https://bugs.llvm.org/show_bug.cgi?id=35051 and attempt to follow hints from https://reviews.llvm.org/D43500 comments.

Reviewers: klimek, ioeric

Reviewed By: ioeric

Subscribers: malcolm.parsons, mgorny, cfe-commits

Differential Revision: https://reviews.llvm.org/D43764

Patch by Jeremy Demeule.

llvm-svn: 329813