Adjust OptionButton icon sizes in PopupMenu automatically

[rsubtil]

Added a max_item_height property to PopupMenus which limits the height of each item. In practice this is used to shrink icons to an acceptable size. OptionButton sets this value automatically to it's current height. (edit: implemented by #75472)

OptionButton nodes now automatically adjust icon sizes from the internal PopupMenu to match the existing icon size when overrided.

Closes #58283 and godotengine/godot-proposals#6139

[KoBeWi]

Needs rebase. I have a bug with stretched icon, but maybe I messed something when trying to fix conflicts

[rsubtil]

#75472 added a icon_max_width field, and since this also adjusts the height automatically, I don't think this PR is necessary anymore. The only change in behavior is the OptionButton automatically adjust the width of PopupMenu icons, so I'll change it to only add that.

This needs to trigger some update if the value is different than the current one.

BTW, I wasn't sure how to do this, was it just calling control->queue_redraw()?

[KoBeWi]

BTW, I wasn't sure how to do this, was it just calling control->queue_redraw()?

Not only. It probably needed something like what's done in set_item_icon_max_width().

[YuriSizov]

I don't think this logic is entirely correct. Button's own icon max size, for example, is applied regardless of the expand mode. This code seems to replicate a small part of the size resolution logic from button.cpp's NOTIFICATION_DRAW handler.

I think we should instead extract that part of the Button's code into a dedicated method and use that method here as well.

[rsubtil]

Yes, I extracted the way the icons were resized when rendered on the NOTIFICATION_DRAW portion. I've implemented your suggestion by moving that math into functions (get_icon_width_with_aspect_ratio(...)) and refactored to use these new methods.

Sorry for the delay, I've been busy the last month, I only had some free time to look at this again now.