Match nuxeo-select with its inner element paper-dropdown-menu

Our nuxeo-select element does not provide some properties available on its inner element paper-dropdown-menu.
Among them are some important to the rendering options:

• horizontalAlign;
• verticalAlign;
• dynamicAlign;

We have `horizontalAlign` hardcoded to `left` and we don't provide a way to configure those while using nuxeo-select.