Provide a sandboxed storage API suitable for implementing a VFS as needed for high-performance applications implemented in WASM such as database engines (e.g. sqlite) or games.

This would require support for paging file system blocks into memory and efficiently flushing changes back to disk.

Note that it is an open question whether or not this could be provided as incremental API additions on top of an existing script-facing sandboxed filesystem API, or whether to satisfy use cases a lower level/more specialized API would be necessary.