el-select 远程搜索下，添加下拉箭头

1. 组件添加class

2. 添加样式 

/deep/ .el-select.remote-select {
  .el-select__caret::before {
    content: "\E6E1";
  }
  .is-focus {
    .el-select__caret:first-child {
      transform: rotateZ(0deg);
    }
  }
}