Extend level crossing in IS by barriers and lights
### Background
currently levelCrossingIS/protection has no children. This is not enough to model complex level crossings.
### Links
* Forum discussion:
* Georg Boasson, 02.06.2022: https://www.railml.org/forum/index.php?t=msg&th=880&start=0&
* Larissa Zhuchyi, 23.01.2024: https://www.railml.org/forum/index.php?t=msg&th=939&start=0&
## Proposed solution railML 3.3
levelCrossingIS/protection should have additional `<barriers>` and `<lights>` children.
both `<barriers>` and `<lights>` should have
* name and spot, linear, areaLocation children.
* @roadSide attribute. Possible values are "left" and "right".
After internal discussion it was decided to change naming to `<roadSideBarriers>` and `<roadSideLights>`.
issue