The goal is to be able to build fully custom tooltips for entire layouts (e.g.
for all `uiBut` for a socket). We already support tooltip callbacks for layouts
and fully custom tooltips for `uiBut`, however not fully custom tooltips for an
entire layout.
This will be used by #140540.
The main noteworthy thing here is that now `uiBut` is passed into the custom
tooltip function. This is necessary when the tooltip still has to be customized
for the exact hovered `uiBut`. For example, we generate a tooltip that applies
to an entire vector socket, but when hovering over e.g. the X input value, the
Python tooltip should show the path for that specific property.
This also fixes a bug in `ui_but_is_interactive_ex` which didn't consider custom
and quick tooltips before.
`uiLayoutSetTooltipCustomFunc` is pretty much the same as its non-custom
counterpart.
Pull Request: https://projects.blender.org/blender/blender/pulls/142044
fc05a70dcd