Expose agui::TableWithSelection to Lua

[curiosity]

It's a table where you can select rows like in a listbox. Example can be found in the multiplayer game browser window.

This kind of table being available will be a massive improvement for mods. Right now any mod that wants even slightly nontrivial functionality from a listbox is forced to roll out its own implementation hacked together from what-have-yous in a scroll pane. These implementations look blatantly inferior to the base listbox because there is no way to spread the selection over multiple GUI elements. This TableWithSelection will provide that way while also removing the complexity of making a custom implementation each and every time, improving UX for both players and mod makers.