Add visibility support to LineBreak

I want to conditionally display a LineBreak based on a visibility condition, so that I can create cleaner and more dynamic parametrization layouts when fields are shown or hidden.

Currently, LineBreak() is a static layout element and does not support the visible parameter available on most other parametrization components. As a result, when fields are conditionally hidden, the associated line breaks remain in place, which can lead to unnecessary whitespace, inconsistent layouts, and reduced usability.

I think this is relevant for the VIKTOR platform because it would improve the flexibility of dynamic parametrizations, provide a more consistent API across parametrization elements, and reduce the need for layout workarounds when building complex user interfaces.

Submitter proposed design (optional)

Support a visible argument on LineBreak, similar to other parametrization elements:

LineBreak(visible=Lookup(“show_advanced_settings”))
or
LineBreak(visible=False)