Codable Support?

[moshe-foreflight]

It would be great if the data models in this library added support for Codable for things like:

1. Passing between an XPC service and a client app.
2. Converting to JSON

I've manually implemented this, because the compiler won't synthesize conformance outside of the main struct/class. Inside of this library, it is likely as simple as adding Codable to the Symbol, SymbolOccurrence and a few other structs/enums.

Happy to open a PR if it would be helpful.

Thank you!

[moshe-foreflight]

Closing per conversation on linked or.