Settings GUI: Hide advanced settings by default

[rubenwardy]

Part of #13476

Adds a new checkbox to show/hide advanced settings, hidden by default. By hiding advanced settings, the settings GUI is less overwhelming.

To do

This PR is Ready for Review.

Questions:

• Resolve the ambiguity between different types of advanced settings (there's both an "Advanced" section and the advanced checkbox now)
• Finalise which settings are considered advanced

How to test

• Run MT, open settings
• Toggle show advanced settings dialog, look at settings
• See all settings marked as advanced in settingtypes.txt

[SmallJoker]

The PR works but I think it would be good to have an indicator which categories that are "advanced". This is especially important for instructing players (wiki, chat). Suggestion: darker background of active and inactive states.

EDIT: Also restore the scrollbar value when ticking the checkbox. Currently it goes back to the top which is rather annoying.

[SmallJoker]

This is very repetitive, especially for mapgens. Would it be much of an effort to add this functionality to entire categories which then propagates the flags to all its contained settings?

[grorp]

Resolve the ambiguity between different types of advanced settings (there's both an "Advanced" section and the advanced checkbox now)

I think this ambiguity is quite confusing. I would prefer it if all advanced settings were moved to the "Advanced" and "Mapgen" categories. Toggling the "Show advanced settings" checkbox would then only toggle the visibility of these two top-level categories.

[rubenwardy]

I'll make a new PR that hides page (IE: mapgen and advanced) rather than individual settings