Skip explorer reveal on visible items

[baileyherbert]

Fixes #82828.

Before this change, clicking on an editor tab while explorer.autoReveal is true would always scroll the explorer so that the corresponding file was vertically centered.

After this change, the explorer isn't scrolled if the corresponding file is already visible in the file tree.

[isidorn]

I think changing this behavior makes sense overall. However I do not like the approach that there are a lot of changes in the tree land.
The tree and list should not be aware of this. I believe you can just use tree api from the explorer to get this behavior.
fyi @joaomoreno

[joaomoreno]

This already exists in the list/tree:

vscode/src/vs/base/browser/ui/list/listWidget.ts

Lines 1576 to 1581 in a7ed9c9

	/**
	* Returns the relative position of an element rendered in the list.
	* Returns `null` if the element isn't *entirely* in the visible viewport.
	*/
	getRelativeTop(index: number): number | null {
	if (index < 0 || index >= this.length) {

So we don't need the list/tree changes.

[baileyherbert]

Thanks guys. Let's try again. 😊

[isidorn]

Works great. Love it.
Even when the user triggers "Reveal active file in sidebar" we center it no matter the visibility which is correct behavior since this is explicitly requirested by user.
Thanks a lot. Merging in.