Storager is the main interface for storage service.
List will list objects under storage.
Create will create an object struct without any API call.
Delete will delete an Object from storage.
Metadata will return current storager's metadata.
Read will read the Object data.
Stat will stat a path to get info of an object.
Write will write data into an Object.
Copy will copy an Object in Storage.
Move will move an Object in Storage.
Reach will get a public url to reach the object.
Multipart will construct an Object via multiparts.
Append will construct an Object via append operations.
Block will construct an Object via blocks.
Page will construct an Object via pages.