Flagpoles and hoisting flags

[mlange-42]

Summary

Content "Flagpoles and hoisting flags"

Purpose of change

Make it possible to hoist flags on flagpoles.

Describe the solution

• Add flagpole furniture: inteded to drop a flag there, which is then displayed as hoisted through tileset's layering.json
  • Metal flagpole, not constructible
  • Wood flagpole, constructible
• Allow for offset in layering variants
  • Saves a lot of work, as offset should be sufficient for hoisted flags in most tilesets
• Allow for other variants (e.g. pride and state flags) in layering (pass them through)
• Add flagpoles to certain "official" and a few other buildings

Other:

• Make street lights and traffic lights not movable

Describe alternatives you've considered

Make hoisting a flag an explicit action.

Testing

Implemented on the tileset side for MSX (see screenshot and PR links).
Visited all modified locations.

Additional context

Made post sprites but no layering yet (needs merge of this):

• Ultica: [Ultica] Flagpoles I-am-Erk/CDDA-Tilesets#1649
• Ultica-ISO: [Ultica-ISO] Flagpoles I-am-Erk/CDDA-Tilesets#1650
• MSX: [MSX] Flagpoles and US flag I-am-Erk/CDDA-Tilesets#1648

Screenshot of hoisted flags in the MSX tileset: