This PR adds prometheus metrics for when users attempt to exceed the
limits for a given resource.
The implementation sets up a second function exported from the
ExceedsLimitError file that records metrics and then throws the error.
This could also be a static method on the class, but I'm not sure that'd
be better.
I've tried to use/add the audit info to all events I could see/find.
This makes this PR necessarily huge, because we do store quite a few
events.
I realise it might not be complete yet, but tests
run green, and I think we now have a pattern to follow for other events.
