Add support for nbt.NBTFile instance in interface.placeStructure

[Niels-NTG]

Inspired by a support request on the GDMC Discord, I've enhanced the interface.placeStructure method to work with the following use case:

nbt = parseNbtFile(path)
interface.placeStructure(nbt, position=(X, Y, Z))

This isn't possible without the changes in this PR, since interface.placeStructure is designed to work with NBT data that is represented as the bytes data type, meaning that the user can only use an existing file or has to find out a way to convert their programatically constructed NBT into bytes themselves. The code in this PR takes care of the latter task, allowing the user to use an instance of nbt.NBTFile as an alternative to bytes.

[avdstaaij]

Hmm, I'd prefer if interface.placeStructure remained as simple and possible, and "high-level" features like this one moved to the not-yet-implemented Editor methods. I do see the value in having this available now though, so I'll merge it, but it's quite likely that I will remove this again when the Editor methods are there.