Added SelectMenu Values slice

[JABirchall]

From what I know, this change is only for modals and is undocumented. They only return the selectmenu name and the values.

[JABirchall]

Update from discord devs, they are waiting for the new release android to ship before releasing SelectMenus They also hinted that they might be rewriting modals ingeneral, as atm they use a webview, and they are thinking and making them native. If they decide to move models to native that will delay future modal additions.