Workers’ compensation — Settlement agreement — Enforceability — Appeals — Appellate court lacks jurisdiction to review order denying employer/carrier’s motion to enforce settlement agreement where order was not final, and did not fall within rule 9.180(b)(1)’s finite list of appealable nonfinal orders — Court rejects argument that serial nature of workers’ compensation cases requires that the term “final order” as used in rule 9.180 be given a modified meaning for purposes of the rule