feat(mlc): Improve Android DX

[grabbou]

There's few challenges with current implementation of Android / MLC, which needs some love if there's enough interest.

That includes:

• adding support for abort and topK parameters on the JSON FFI Engine
• figuring out UI freeze first time request is run

Rather than that, it all works quite smoothly. Until that is resolved, I would not recommend using MLC in production. We will look into other SDKs for that.

[artus9033]

Possibly related: mlc-ai/mlc-llm#1401