Re-use disposable store while rendering elements (#163398)
Re-use disposable store while rendering elements (#163398)

While rendering, the tree renderer currently creates a `DisposableStore` every time `renderElement` is called. For better performance, we should instead re-use a disposable store that is stored on the template data

I've also moved some cleanup logic to  `disposeElement` instead of putting it in this store. This avoids creating and registering extra disposables
microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode,microsoft/vscode