JupyterLab makes the assumption that the IDefaultDrive is HTTP-based in a couple of places

Description

In here we make the assumption that drive.get would raise a 404 error: https://github.com/jupyterlab/jupyterlab/blob/badad6eb5c7654403acf70843b21f18b5a5b8445/packages/docregistry/src/context.ts#L326 In here we make the assumption that drive.rename would raise a 409 error: https://github.com/jupyterlab/jupyterlab/blob/badad6eb5c7654403acf70843b21f18b5a5b8445/packages/docmanager/src/dialogs.ts#L211

These assumptions are making e.g. JupyterLite not behave correctly. For example, "Save As" does not work currently in JupyterLite.