Make tree view more stable

<!-- ⚠️⚠️ Do Not Delete This! feature_request_template ⚠️⚠️ --> <!-- Please read our Rules of Conduct: https://opensource.microsoft.com/codeofconduct/ --> <!-- Please search existing issues to avoid creating duplicates. --> <!-- Describe the feature you'd like. --> ## Make tree view UI more stable When I'm using the tree view, I often find myself losing the item I'm working with and needing some moment to re-discover it. I have found a reproducible scenario in which this happens and recorded a video of it. ### Video https://user-images.githubusercontent.com/153391/193243131-34b66936-bde2-4969-a8da-161a2a4327ef.mov ### Description Basically, when I create a new folder below an existing one, the tree view will add a new item below the folder and expand that folder to make it visible. I am assuming that there is some code there that makes sure that the new item will be in view (which makes sense), but that code is a bit heavy-handed and often the tree view will scroll even when there seems to be no real reason to do so, causing a disconcerting jump making me lose track of where the item I'm working with is and having to re-discover it. This takes me out of my focus and happens quitte often, because the tree view is such a central widget in the VSCode UI. I found that whether this happens or not and how far the jump will be seems to be related to the length of the scroll bar and the position of the folder you create a new item under. Ironically it seems to be worse when the item is high up in the view, even though that actually means that there is no need to scroll at all. I expect this scrolling to occur only when really needed. In general I'd like to be in control of the scrolling as much as possible, so that the position of all items remains stable unless I change it myself. ### Feature or bug, you decide I'm posting this as a feature request, but some might consider it a bug... I see you have 5K issues already, so probably this one would have low priority, but when…