Expose and rename ItemList's _check_shape_changed to force_update_list_size

[Spartan322]

Closes godotengine/godot-proposals#254

Exposes force_update_list_size to allow users to update auto_height_value early before draw if shape_changed is true, can be retrieved via get_minimum_size().

Exposed Additions

ItemList:

func force_update_list_size()

[Spartan322]

Its probably better with this PR to also expose the auto_height_value as a getter, as in cases where auto_height is false its impossible to tell what the current is still without introducing code smells: (and it still calculates it regardless of auto_height)
Current solution this provides:

# changed list without auto_height enabled
force_update_list_size()
auto_height = true
var height = get_minimum_size().y
auto_height = false
# ...

But if auto_height_value is exposed and updates could be forced then both the code and documentation becomes more readable and doesn't require this janky solution:

# changed list without auto_height enabled
force_update_list_size()
var height = get_auto_height()
# ...

[KoBeWi]

The PR looks ok. I guess it doesn't hurt to add the new function if it has some uses (and it's huge, so replicating it isn't exactly simple). The other function you mention has easy workaround and is rather specific, so it should be added in another PR if anything (and probably needs separate proposal).

I'm wondering if the name can't be better though. Maybe it should be update_auto_height().

[KoBeWi]

I think the method description might still need an improvement, but I don't have any suggestion. Other than that the PR looks ok.

[akien-mga]

The CI failure was my fault (now fixed), will need a rebase to solve it.

[Spartan322]

I'm not exactly sure what would be the best recommendation for this as of a2a524d, as that accomplishes majorly the same functionality except it doesn't expose it, which is fine, but would it be better to rename _check_shape_changed to update_auto_height or merely expose it as such in the bindings? Or should the underscore in the name simply be removed and expose it as that, the name makes it sound kinda incorrect for a regular user, its kinda like a try_update type of behavior. Regardless I could also use this PR to update the comments to reflect the comment style.

[YuriSizov]

@Spartan322 If we're exposing it, it can be named force_update_list_size. Calling it anything auto_height would be a misnomer. Note that "list" is there so that the method is not named too generically to avoid conflicts with classes higher up the inheritance chain.

There is no reason to have different names publicly and privately, so you can can just rename the method and make it public, and expose it with the same name to the API.

[YuriSizov]

See above.

[YuriSizov]

Other than the docs, this seems fine to me.

[akien-mga]

Thanks!