[clang-format] Fix inconsistent annotation of operator&

Token annotator incorrectly annotates operator& as a reference type in
situations like Boost serialization archives:
https://www.boost.org/doc/libs/1_81_0/libs/serialization/doc/tutorial.html

Add annotation rules for standalone and chained operator& instances while
preserving behavior for reference declarations at class scope. Add tests to
validate annotation and formatting behavior.

Differential Revision: https://reviews.llvm.org/D141959