Admin only way of enabling un-restricted rendering of forum posts/responses

[the-Bruce]

The forum is used for several soc specific announcements, such as AGM. It may be worth adding a setting that allows a web admin (or person with sufficient permissions?) to enable un-restricted rendering within an existing post so that more advanced formatting can be achieved. Technologically, this would not be difficult to achieve. Would be interested in peoples thoughts.

[the-Bruce]

We would now need to also update the preview endpoint to reflect the change