new feature: build Fs Accessor within async IO operations

[dentiny]

Feature Description

I notice when we create an operator for local filesystem, it actually issues sync IO requests.

opendal/core/src/services/fs/backend.rs

Lines 90 to 100 in b53d802

	// If root dir is not exist, we must create it.
	if let Err(e) = std::fs::metadata(&root) {
	if e.kind() == std::io::ErrorKind::NotFound {
	std::fs::create_dir_all(&root).map_err(|e| {
	Error::new(ErrorKind::Unexpected, "create root dir failed")
	.with_operation("Builder::build")
	.with_context("root", root.to_string_lossy())
	.set_source(e)
	})?;
	}
	}

While all other operations are async (i.e., read, write, etc), people are likely to use Operator in an async runtime, would be better if operation build is also async.

Problem and Solution

Proposed solution:

• Make operator creation async, essentially use async IO syscalls.
• But it's a breaking behavior and API change, likely we will add another async interface.

Additional Context

No response

Are you willing to contribute to the development of this feature?

• Yes, I am willing to contribute to the development of this feature.

[Xuanwo]

I think we can just move this check later and down to run time.

[machichima]

Hi @Xuanwo
I would love to work on this
Thanks!