Show file names in remove files confirmation dialog

[pafuent]

Closes #85261
Supersedes #85290

Thanks to @jsjtxietian that implemented most of the code. I just rebased the original PR and did some tweaks to adjust ItemList and Tree sizes.

[pafuent]

Can I get a review?

[akien-mga]

Seems good to me.

[jsjtxietian]

LGTM

[KoBeWi]

The dialog looks confusing when deleted file is a dependency:

There should be some label between the 2 boxes.

Also when deleting single file, the item list is scrollable by a pixel:

[pafuent]

Also when deleting single file, the item list is scrollable by a pixel

@KoBeWi I tried a lot of different things trying to know the size of one tree item to set the minimum size of the tree. My plan was to have the size of 5 items as max (for less items just set it to see all the items)
The best approximation are this lines:

if (tree_item_count > 0) {
	const uint32_t multiplier = MIN(tree_item_count, 5);
	owners->set_custom_minimum_size(Size2(0, 35 * multiplier) * EDSCALE);
}

Is there a better way to know the exact size of a tree item?
(sadly my knowledge on Godot GUI is limited)

[KoBeWi]

There is get_minimum_size() method in TreeItem.

[pafuent]

After trying several methods to set a custom minimum size, I decided to just use one with a fixed value to keep the code simpler.

[Repiteo]

Thanks!