Make lifts manage their own doors

[luca-della-vedova]

Feature request

Description

Make lift simulation plugins manage their own doors, instead of using door plugins.

Implementation considerations

Currently, lift doors are commanded through a door plugin. While this works, the architecture is fundamentally wrong since the simulated lifts will publish a request to the door_supervisor to request opening a lift door, which runs a door plugin.
In reality, lifts would manage their own doors and wouldn't need to go through RMF to operate them.
Additionally, since lift doors are running door plugins they also appear in the rviz door panel, which shouldn't be the case since RMF is not managing the doors individually, i.e. in the hotel world from rmf_demos: