Change custom view multiselect array to have all selected

Fixes #79982

src/vs/vscode.d.ts

@@ -6886,7 +6886,7 @@ declare module 'vscode' {
 		/**
 		 * Whether the tree supports multi-select. When the tree supports multi-select and a command is executed from the tree,
 		 * the first argument to the command is the tree item that the command was executed on and the second argument is an
-		 * array containing the other selected tree items.
+		 * array containing all selected tree items.
 		 */
 		canSelectMany?: boolean;
 	}

src/vs/workbench/browser/parts/views/customView.ts

@@ -856,12 +856,7 @@ class MultipleSelectionActionRunner extends ActionRunner {
 		const selection = this.getSelectedResources();
 		let selectionHandleArgs: TreeViewItemHandleArg[] | undefined = undefined;
 		if (selection.length > 1) {
-			selectionHandleArgs = [];
-			selection.forEach(selected => {
-				if (selected.handle !== context.$treeItemHandle) {
-					selectionHandleArgs!.push({ $treeViewId: context.$treeViewId, $treeItemHandle: selected.handle });
-				}
-			});
+			selectionHandleArgs = selection.map(selected => { return { $treeViewId: context.$treeViewId, $treeItemHandle: selected.handle }; });
 		}
 
 		return action.run(...[context, selectionHandleArgs]);