[libc++] Remove recursion in basic_string::insert(const_iterator, ForwardIterator, ForwardIterator)

`__addr_in_range` is a non-constexpr function, so we can't call it during constant evaluation.

Reviewed By: Quuxplusone, #libc, miscco

Spies: miscco, libcxx-commits

Differential Revision: https://reviews.llvm.org/D119633