JSON-RPC 3.x: Update object imports

Problem/Motivation

Need to update to adjust for 📌 [PP] 'object' is a reserved keyword as of PHP version 7.2 and should not be used in namespaces Fixed . Unfortunately this means we can't support 2.x and 3.x at the same time, so we will support 3.x in this MR for now, and later commit it when we drop support for 2.x.