Enhance BoM Handler to support 2412 XSD

[Andy-Grigg]

The new 2412 XSD schema for bills of materials supports transport and location child nodes for additional node types. The builder needs to be enhanced to allow these new features.

We should consider as well if we want to continue to support the current 2301 format. A few thoughts on this:

1. Completely duplicate all the BoM building code and leave the old version as-is
2. Use different methods, or arguments in a method, to control which version we serialize to

Second option is better, but we'd need to handle how to serialize objects that cannot be represented in older BoM formats. Maybe raise an exception if these are encountered? Or delete them and warn?

Either way, we need to make sure this is an additive change, so scripts written against the previous version of the BoM handler continue to function. This probably means option two, using an argument to determine the BoM output. We should be able to default to the latest version, and offer an override if needed.