Disable price set options when max participants is reached

Price set options have the super useful feature to allow up a limited number of event participants.

It'd be great to improve this further and disable the option once that number is reached.

Currently users have no way of knowing that a price set option is full until they attempt to register for it.
If most options are full, it results in a frustrating experience trying to submit an event registration form multiple times with different options.

On the backend side of this, this means that admins have to keep an eye on all price options and their participants and manually disable those when the become full.