Insurance — Property — Standing — Assignment — Validity — Assignment of insurance benefits was invalid and unenforceable where it did not include the statutorily-mandated written, itemized, per-unit cost estimate of services to be performed — Separate estimate of services to be performed did not satisfy requirement where estimate was not signed by plaintiff assignee and did not include all services that were performed — Letterhead with assignee’s name printed at top of estimate did not suffice as assignee’s electronic signature