Create sequenced message type [#3178]
Closes #3178 (closed). Creates a sequenced message type, moves source, destination, and header to the sequenced message type, and refactors the relevant code.
Changelog: refactor
Closes #3178 (closed). Creates a sequenced message type, moves source, destination, and header to the sequenced message type, and refactors the relevant code.
Changelog: refactor