Add missing classes and styles for the media slide overlay responsive options

Not sure how to handle older drowl_base theme versions (Foundation).

As mentioned in the module description, we use Bootstrap classes - old (Foundation based) themes will need to override the affected media templates.

The media templates in 4.x were switched from Foundation to Bootstrap (#3436181: Replace Foundation Twig Templates with Bootstrap Templates) but 4.x will generally also allow to be used with Foundation by overriding and updating the templates.

@anybody: We hide overlay fields, when "no overlay" is selected (States API). Could you please remove this? It doesnt make sense, since we can disable the overlay for specific breakpoints.

The trigger field is: field_overlay_position, please fix it right here in the issue fork so we dont run into merge conflict ..things.

@anybody: Okay.. there are still fields that should be hidden by States API, so more explicit.. never hide those three:

- field_overlay_display
- field_overlay_button_color
- field_overlay_button_style

While:
- field-overlay-sizing should be hidden when field-overlay-position is set to "disabled" (or unset) => this is already the case
- field_overlay_sizing_md should be hidden when field_overlay_position_md is set to "disabled" (or unset)
- field_overlay_sizing_lg should be hidden when field_overlay_position_lg is set to "disabled" (or unset)

The field states are managed in the wrong module (drowl_header_slides), it doesn't matter if the media slide is a "header slide", a hero or a regular slide.

I'll move it over, so we can finish and release this.

Done. Please review @anybody, I'll create a new release afterwards.

I also create a new release of drowl_header_slides without the media slide form fields states stuff.

I'll create another task for the required configuration update, which is not that important.

Use the empty value instead of "disabled" string for the disabled option

See #3497194: Make media-slide overlay responsive settings mandatory and provide default values, so we dont have an empty value anymore after this change.

Add the configuration updates here, or it will never happen, which will screw up existing projects

I don't think we have any configuration updates.

Merged! thx!