Work on converting the course format renderer to templates

Currently Moodle's course formats are run heavily though the renderer in course/format

This can be better handled as it primarily echos out html_writer items, we can add new functions to better build our renderable objects and parse them with templates.

Doing this would have at least a couple of big benefits:

1. Help ease developers pains in tracing diverging code paths
2. Allow course format creators and themes customise the look and feel of a course format without creating a new course format for the same functionality but different styles