src/vs/workbench/contrib/notebook/browser/notebookCellStatusBarServiceImpl.ts/NotebookCellStatusBarService/registerCellStatusBarItemProvider
class NotebookCellStatusBarService:	registerCellStatusBarItemProvider(provider: INotebookCellStatusBarItemProvider): IDisposable {
		this._providers.push(provider);
		let changeListener: IDisposable | undefined;
		if (provider.onDidChangeStatusBarItems) {
			changeListener = provider.onDidChangeStatusBarItems(() => this._onDidChangeItems.fire());
		}

		this._onDidChangeProviders.fire();

		return toDisposable(() => {
			changeListener?.dispose();
			const idx = this._providers.findIndex(p => p === provider);
			this._providers.splice(idx, 1);
		});
	}