IFC5-alpha implementation in IfcOpenShell-Python

IFC5 (alpha) is a new standard in development by buildingSMART International https://github.com/buildingSMART/IFC5-development/ where the traditional Express-based (ISO 10303) schema and serialisation technologies are replaced by more modern JSON alternatives.

The aims of IFC5 are to enable:
- Shared ownership of data (by means of layers that can be composed together)
- Incremental updates and non-monolithic exchanges (also by means of layers or imports)
- Easy to implement, modern technologies with less indirections
- Extensibility and modularity of schemas
- Traceability of information
- Reliability and less ambiguity

Within this project the aim is to prototype such IFC5-workflows initially in our Python libraries because:
- In Python it's more easy to adapt to rapidly changing developments
- We can use performant JSON parsers such as orjson
- The high-level ifcopenshell.api provides a nice means for abstraction and is only available in python
- The ifcopenshell.file based transaction/history mechanism provides a nice entry-point to map to the layer-based incremental writing and is only available in Python

Budget tiers:
- $  5.000 -> alternative ifcopenshell.file back-end with support for composition, ifc5 support for some API calls
- $ 10.000 -> layer-based authoring mechanisms in Bonsai UI
- $ 15.000 -> mapping of Bonsai data to published ifc5 schemas