Atlas should handle garrisoned units

[mimo]

With #2984, maps can have garrisoned units (useful for example for nomad sea map). This is set in the script map in its xml file. If holder is the GarrisonHolder entity, and ent1, ent2, ... the entities to garrison, the script would be

<Script><![CDATA[ let cmpGarrisonHolder = Engine.QueryInterface(holder, IID_GarrisonHolder); if (cmpGarrisonHolder)

cmpGarrisonHolder.initGarrison = [ent1, ent2, ...];

]]></Script>

Atlas should be able to deal with such garrisoned units:

• find a way to display garrisoned units
• generate such a script from all garrisoned units when saving a map