Opendal support sync read/write API

[sundy-li]

For local fs, we can switch into sync read/write API to improve the performance

[Xuanwo]

tokio is much slower

• fs is based on tokio::fs
• bfs is a simple wrapper by blocking

On NVMe SSD

On tmpfs (in memory)

[Xuanwo]

So the conclusion is:

• tokio::fs is so slow that maybe we should not use it for our fs backend.
• It's worth to provide a sync version API
• We need to develop a real async io fs backend based on aio or io_uring: see Async fs support #19