Allow having a max_values higher than 25 for the new select menu types.

[didinele]

As the title says, the new select menu types (roles, users, mentionables, channels) only allow a max_values of up to 25. This is counter-intuitive and defeats a lot of use cases (i.e. where the user is able to select an arbitrary amount of roles) and presumably an oversight from the string select menus.