tree - support expandAll or equivalent

[jrieken]

re #64727

When filtering or find items in the outline all matches are highlighted and revealed. See https://github.com/Microsoft/vscode/blob/ca773cb3f27afd57b0bd790d2e2f33f261a31030/src/vs/workbench/parts/outline/electron-browser/outlinePanel.ts#L570-L577

There is no equivalent in the new tree, except for calling expand in a loop. After #64807 (comment) I am not sure anymore that's OK to do

[joaomoreno]

We can easily do this in the ObjectTree now. I can even add in the Alt clicking that would do this per subtree.

[joaomoreno]

Alright did a pretty big revamp of the collapse feature set in the tree:

• Introduced expandAll
• Introduced a recursive flag for setCollapsed and toggleCollapsed
• Holding Alt while expanding/collapsing a node via mouse click or Spacebar will now perform the action recursively, just like in native tree widgets (finally we get this!).

Here's the current full extent of collapse related methods of the tree:

collapse(location: TRef, recursive: boolean = false): boolean;
expand(location: TRef, recursive: boolean = false): boolean;
toggleCollapsed(location: TRef, recursive: boolean = false): boolean;
expandAll(): void;
collapseAll(): void;
isCollapsible(location: TRef): boolean;
isCollapsed(location: TRef): boolean;

cc @isidorn @roblourens

[isidorn]

@joaomoreno any chance that you support expandAll(elements?: T[])
Currently I have to do the following
https://github.com/Microsoft/vscode/blob/ab0b87329f1e5c89f1df6e50c5a4b7e7a37006dc/src/vs/workbench/parts/files/electron-browser/views/explorerView.ts#L970

Also that expand and others throw errors when an element is not there is forcing me to use these ugly ignoreErrors approach.