refactor: refactoring http request creation and sending (#395)

* refactoring http request creation and sending

* fix lint error

* increase the test coverage of client.go

* refactor: Change the style of HTTPRequestBuilder.Build func to one-argument-per-line.

moderation.go

@@ -63,7 +63,7 @@ type ModerationResponse struct {
 // Moderations — perform a moderation api call over a string.
 // Input can be an array or slice but a string will reduce the complexity.
 func (c *Client) Moderations(ctx context.Context, request ModerationRequest) (response ModerationResponse, err error) {
-	req, err := c.requestBuilder.Build(ctx, http.MethodPost, c.fullURL("/moderations", request.Model), request)
+	req, err := c.newRequest(ctx, http.MethodPost, c.fullURL("/moderations", request.Model), withBody(&request))
 	if err != nil {
 		return
 	}