suggestion: make attributes of building window accesible via lua

[hessenfarmer]

for scenario design it would be helpful to access the following properties of a visible Building window via lua:
1. the building name (e.g. empire_farm)
2. the serial number of a building (e.g. 3257)
3. the economy the building belongs to
4. the player # who is owner of the building
5. the workingstate of the building (e.g. stopped or working; this would be very interesting to be RW if possible)

[GunChleoc (gunchleoc)]

Migrated to https://github.com/widelands/widelands/issues/3226