Ozone + MaterialUI: Add option to only show sublabel for selected entry

[Ryunam]

Description

A quick look at the XMB menu driver (which I don't use that much anymore) got me thinking about a nice little customization option for both Ozone and MaterialUI (especially the former), which I think looks quite nice and is pretty convenient to have for experienced users.

This PR adds a new option under Settings -> User Interface -> Appearance -> Menu Item Visibility, called "Show Menu Sub-Labels only for Current Selection". It is only visible when using either the Ozone or the MaterialUI menu driver and it defaults to OFF.
Enabling it makes the menu display the respective sublabels only for the currently highlighted menu entry/option.

The advantage of this implementation is in having the best of both worlds:

• users can still see the sublabel description for the currently selected option, as normal;
• at the same time, they retain the ability to quickly and extensively look at all the entries/options present in the page, as if sublabels were universally disabled, and quickly figure out where to go / what might need tweaking.

It works particularly well with Ozone, where as a consequence of the selective display of sublabels the adjusted spacing of the menu provides a more compact view at a glance.

This is how it looks on Ozone:

2026-08-18.12-43-17.mp4

This is how it looks on MaterialUI, where the advantage is much less notable due to the way the menu entries are spaced by default:

Despite the minor improvement gained with it on MaterialUI, I decided to implement the option there as well, for the sake of consistency and for potential future benefits that might affect the menu driver.

Reviewers

@LibretroAdmin