inside `parseMessageForMUCCommands`.
If the function doesn't find any core MUC commands, it calls
`parseMessageForCommands` which will trigger the hook.
I think it's appropriate to give built-in commands preference above
commands by 3rd party plugins and this also solves the issue of the hook
being triggered twice (once in `parseMessageForMUCCommands` and
then again in `parseMessageForCommands`).