Errors in pkg/* do not comply with GSP-47 & GSP-51

[xxchan]

They will become ErrUnexpected. (What should they become?)

e.g., qingstor:

func newServicer(pairs ...typ.Pair) (srv *Service, err error) {
	defer func() {
		if err != nil {
			err = services.InitError{Op: "new_servicer", Type: Type, Err: formatError(err), Pairs: pairs}
		}
	}()
	
	//...

	cp, err := credential.Parse(opt.Credential)
	if err != nil {
		// credential.Error here
		return nil, err
	}

	//...

	if opt.HasEndpoint {
		ep, err := endpoint.Parse(opt.Endpoint)
		if err != nil {
			// endpoint.Error here
			return nil, err
		}
	
	//...
}

[Xuanwo]

Maybe they should implement IsAosError either?