Experiment — Error handling for HTTP capability

[StuartHarris]

Experimenting with what it could look like to thread Result types through the core (e.g. for Http Capability)

Notes:

• Had to temporarily remove the deserialisation in the capability (e.g. getJson()), but might be able to add it back later
• Thought that aliasing Result<HttpResponse, HttpError> to HttpResult might flow through into the type generation to avoid name clashes, but it appears not to. We might need to find another solution to this (e.g. multiple output files, also see [Bug] Swift types prefixed by module name zefchain/serde-reflection#22 (comment))
• the wasmpack plugin for nextjs doesn't support the cargo workspace hoisting of package fields, so had to remove this for the shared libs (although it seems the dependency hoisting is OK).