Refactor core modifying GUI to use add_trait and deprecate the whole tooltip system

[openly-retro]

• in the pick effect:
• • put the add_trait_no_notify command at the top of the effect
• Then where this effect is called
• use the "cost" tooltip

So the principle is:

1. use the in-game system to show the trait tooltip
2. scope the button effect to the ruler
3. show our custom "cost" tooltips

[openly-retro]

councilor buttons don't use a custom tooltip, they take advantage of the game's inbuilt trait tooltip effect. however, when there arent enough trait points, the tooltip isn't shown, and the gui simply says "not enough trait points"

perhaps the trait tooltip generation system should not distinguish between councilor and leader and ruler. instead, have one common trait tooltip shared between all GUIs, and all classes common traits shared by multiple classes have the same effect, so unique trait tooltips per class aren't needed

using a format like xvcv_mdlc_trait_gui_tooltip_leader_trait_defence_engineer_2 or some such not going to refer to councilor, class, scientist, etc.. just the namespace, some sort of stem, and then the trait name