Add LLM Inferencing Support

[endocrimes]

This is an initial pass at adding LLM Inferencing support to they Python SDK. Demo in the cloud: https://spin-py-hello-llm-2zjy1qai.fermyon.app

Quirks:

• There isn't a "good" way to expose a rust enum to python, so we make the model a string and map it to internal sdk constants / the other associated enum type

[dicej]

LGTM. Thanks for doing this!

BTW, this is how wasmtime-py and componentize-py would represent a variant type like InferencingModel in Python:

from typing import Union
from dataclasses import dataclass

@dataclass
class InferencingModelLlama2Chat:
    pass

@dataclass
class InferencingModelCodellamaInstruct:
    pass

@dataclass
class InferencingModelOther:
    value: str

InferencingModel = Union[InferencingModelLlama2Chat, InferencingModelCodellamaInstruct, InferencingModelOther]

I think using a string in this case is fine, but for future reference the above is also an option.

[endocrimes]

huh til about dataclasses! (I haven't seriously python'd in a very long time 😅, and the pyo3 issues were unhelpful 😂 )