add declared type namespace to json

[Mythra]

👋 Thanks for this tool! I've been writing some tooling to automatically dump things from GHIDRA, and currentlyt he dump takes ~4 hours because it's just dumping everything in the metadata.json. I was looking to filter out dumping any Mono/System methods, in order to do that because there may be conflicting names without namespaces I figured I'd just add the namespace to the JSON, and filter on that.