Update to MAPv4 public draft

This should be in line with the draft at: https://docs.google.com/document/d/1Jh8ULpw0jb8kyxV-Ygw9U0n-XqXkM6_V3jxfmnkebqo/edit#
Not a specific issue with the changes, but worth mentioning. Changing `edm:dataProvider` to be an instance of `edm:Agent` could (or will?) impact its JSON-LD serialization (ie. moving from a string literal to an object or a URI).