Initial nested options implement

[Saplonily]

Closes #1015

This pr also fix submenus not being expanded by its items. (It's calculated but not used somehow, I don't know much about the details 🤔)

Absolutely this will make search box a bit useless, or should we have a feature that search box can search into nested menus?

[SnipUndercover]

Doesn't this conflict with #1005?

[Saplonily]

Doesn't this conflict with #1005?

It's not the same "nest" way as it, it just focus another menu when entering a "submenu". Since we have true nested submenu supports in it, I can then base this implement on it later🤔

[Saplonily]

Tried using 'true' submenus, but it looks a little ugly. I personally would prefer this previous implement.

[Wartori54]

Looks like a solid new way to organize the mod options menu, I'd say that if we roll with it we should completely swap to that (so no NestedOptions toggle), but I can understand why people would like to have the ability to return to the current one. And definitely doesn't conflict with #1005 .

About the search option, it could still be useful regardless for overwhelmingly large mod option sections, and to search in the new initial options menu.

Given that this is a design focused PR I'd like other people to come in and share their opinion on this too.