[clang-tidy] Extend UnnecessaryCopyInitialization check to trigger on...

[clang-tidy] Extend UnnecessaryCopyInitialization check to trigger on non-const copies that can be safely converted to const references.

Summary:
Move code shared between UnnecessaryCopyInitialization and ForRangeCopyCheck into utilities files.
Add more test cases for UnnecessaryCopyInitialization and disable fixes inside of macros.

Reviewers: alexfh

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D17488

llvm-svn: 262781