Allow seperate Serialization of a unit's instructions and debug info

[therealbnut]

Hi,

As discussed on the discord:

Hey, is it possible to round-trip serialise/deserialise a Unit as bytecode? Ideally as a tuple with debug info seperate.

This is the cleanest way I could think of to seperate them.

We could remove the Deref/DerefMut if we're happy to change self. to self.data in most uses within this file.

I believe it should be compatible with existing serialisations, so shouldn't break anything. However I haven't made any tests for that, I wasn't sure if any already existed.

[udoprog]

Looks good to me with some minor changes.

UnitData should only be called Data. We've gone down the route of naming things according to their modules before, but the style I'm trying to enforce now is to avoid it.

That being said, Data is very generic. Maybe a better name for that and fn data() could be found. But if not I wouldn't sweat it.

[therealbnut]

That being said, Data is very generic

Yeah, I couldn't think of a better name, which is why I went with UnitData. They are inherently tied together. I think it's not so much that it belongs to the module, it's that it's an inherent part of the Unit, like saying "piano key" rather than "key".

[udoprog]

Cheers!

[therealbnut]

Thanks for the review!