Support creating dir

[Xuanwo]

Although s3 doesn‘t need to support creating dir, we need to keep fit with fs.

[D2Lark]

azblob also don‘t support create dir directly as well ,I thought maybe need
to create /a/b/c and delete object c

[Xuanwo]

On object storage system like s3 and azblob, I think we can create an object ends with / like a/b/c/.

[D2Lark]

i just check azure cli and found this, so this function should work on azblob. sdk is too heavey i even don't want download aws sdk for rust

[Xuanwo]

sdk is too heavey i even don't want download aws sdk for rust

That is why we are migrating to reqsign instead, let's make API simple again.

[Xuanwo]

I'm working on the design of creating new dir.

[Xuanwo]

Should be addressed by proposal: #221

[Xuanwo]

Fixed in #222