[form-layout] Add FormItem and labelsAside support to autoResponsive mode

[vursen]

Add a labelsAside property that, when enabled, configures <vaadin-form-item> elements to display labels horizontally next to the fields. If the container doesn't have enough space, it should automatically switch to the default "labels above" mode and back when its width gets bigger again. By default, labels in <vaadin-form-item> should be displayed above the field, which is opposite to the FormLayout's existing behavior with responsiveSteps.

Part of vaadin/platform#7172