extensions/references-view/src/extension.ts/activate
export function activate(context: vscode.ExtensionContext): SymbolTree {

	const tree = new SymbolsTree();

	references.register(tree, context);
	calls.register(tree, context);
	types.register(tree, context);

	function setInput(input: SymbolTreeInput<unknown>) {
		tree.setInput(input);
	}

	return { setInput };
}