Add shortcut to Collapse All Trees in Outline View (#74026)

* Add universal list collapseAll keybinding

This adds the ability to perform a collapse all on a full tree upon a keyboard shortcut. Upon performing the shortcut, it will collapse every node on the tree.

src/vs/workbench/browser/actions/listCommands.ts

@@ -302,6 +302,24 @@ KeybindingsRegistry.registerCommandAndKeybindingRule({
 	}
 });
 
+KeybindingsRegistry.registerCommandAndKeybindingRule({
+	id: 'list.collapseAll',
+	weight: KeybindingWeight.WorkbenchContrib,
+	when: WorkbenchListFocusContextKey,
+	primary: KeyMod.CtrlCmd | KeyCode.LeftArrow,
+	mac: {
+		primary: KeyMod.CtrlCmd | KeyCode.LeftArrow,
+		secondary: [KeyMod.CtrlCmd | KeyMod.Shift | KeyCode.UpArrow]
+	},
+	handler: (accessor) => {
+		const focusedTree = accessor.get(IListService).lastFocusedList;
+
+		if (focusedTree && !(focusedTree instanceof List || focusedTree instanceof PagedList)) {
+			focusedTree.collapseAll();
+		}
+	}
+});
+
 KeybindingsRegistry.registerCommandAndKeybindingRule({
 	id: 'list.expand',
 	weight: KeybindingWeight.WorkbenchContrib,