[clang-format] Treat &/&& as reference when followed by requires clause

Previously, the token annotator would get confused and annotate a member
function's ref qualifier as a binary operator, if said function also had
a requires clause after it.

This patch accounts for that, treating requires clauses more similarly
to `noexcept`, which also comes after the ref qualifier.

Fixes https://github.com/llvm/llvm-project/issues/61270

Reviewed By: HazardyKnusperkeks, owenpan

Differential Revision: https://reviews.llvm.org/D145656