HMS-2714 stop processing if input validation fails

Currently input validation failure does NOT cause processing to
stop.  If somehow the backend operation succeed, that can result in
a 400 Bad Request response, but the target backend operation
completed and database modifications potentially performed.
Also, the normal response data gets appended to the error message.

Update the validation middleware to stop processing when an input
validation error occurs, after setting the response status and body
content (error message).  As a result, no further processing will be
performed.

internal/infrastructure/middleware/validate_api.go

@@ -262,6 +262,7 @@ func RequestResponseValidatorWithConfig(config *RequestResponseValidatorConfig)
 				if err != nil {
 					c.Response().Header().Set(echo.HeaderContentType, "text/plain")
 					c.String(http.StatusBadRequest, err.Error())
+					return nil  // stop processing
 				}
 			}