Add methods to get target filter and repeat

[KoBeWi]

get_texture_filter() and get_texture_repeat() in CanvasItem return the filter/repeat of the current node, but if it's set to "inherit", the returned value isn't what one would expect. To get accurate value, you'd need something like is_visible_in_tree(), but for filter and repeat.

Luckily such thing exists and it's called texture_filter_cache and texture_repeat_cache. This PR exposes these properties via public methods get_target_texture_filter() and get_target_texture_repeat().

This is needed for #60149 and #57596
The methods are not exposed to scripting for now.

[clayjohn]

Looks good to me!

[groud]

Looks good to me, my only concern is the naming which it kind of weird, as I am not really sure what "target" means here.
I think a more adequate naming should probably copy the one for CanvasItems' visibility, which uses is_visible_in_tree(). Thus I think it could be renamed to get_texture_filter_in_tree() and get_texture_repeat_in_tree()

[KoBeWi]

Renamed.

[clayjohn]

Looks great! Thanks

[reduz]

I think this PR is good and it makes sense it was merged, but given this is core engine I would appreciate being asked next time.

[reduz]

Anything SceneTree or core nodes (Node, CanvasItem, Control, Node2D, Node3D, Viewport, etc) is core.

[MrBlockers]

I'm making use of this for #67288 but discovered that it doesn't seem to respect the default texture filter project setting when the all of the nodes up the tree are set to inherit. It seems like it's giving me linear in a project where all the nodes are set to inherit but the project setting is nearest. Should I open an issue for that?

[KoBeWi]

Yeah that sounds incorrect.