- Refactor lfs request code
- The original code uses `performRequest` function to create the
request, uses a callback to modify the request, and then send the
request.
- Now it's replaced with `createRequest` that only creates request and
`performRequest` that only sends the request.
- Reuse `createRequest` and `performRequest` in `http_client.go` and
`transferadapter.go`
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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>