Hide the Cloud size and position controls when clouds are disabled

Similar to #1454, make `Cloud size`, and `Cloud X`-`Z` collapsible, and hide them when `Enable clouds` is not selected. I think this will just aid in decreasing overall visual clutter, particularly because the position options don't actually provide meaningful information unless you've got clouds enabled.
In the pull request where I first brought this up I mentioned hiding the sun controls based on `Draw sun` being disabled, but I've now realised that's not actually desirable or correct behavior, so I think they should stay as they are currently.

Review issue #1454 for the related collapsible-control pattern, then search the Java UI code for the labels `Cloud size`, `Cloud X`, `Cloud Y`, `Cloud Z`, and `Enable clouds`. The change is done when those cloud controls are collapsible and hidden when clouds are disabled, while the sun controls retain their current behavior.

Written by the indexing model from the issue text.