bindings/c: Make sure API is consistent by removing blocking

              I found an issue that our naming for structs and functions is inconsistent. The word `blocking` shown up randomly.

cc @Ji-Xinyou, how about removing all `blocking` from our API for now? We can add `async` version in the future.

_Originally posted by @Xuanwo in https://github.com/apache/incubator-opendal/issues/3259#issuecomment-1762558075_
            