Run river flow ML model in krustlet

[jiayihu]

Epic #56

[jiayihu]

The ONNX model can read the Tensorflow model and be compiled to WASI. Some caveats:

• I had issues with wasmtime CLI option --dir=. when used with --invoke. It doesn't seem to work and it throws stating that the file capability handle is not available.
• The OCI image doesn't support anything else then the WASM module itself for now. Surely krustlet doesn't support it. So the ONNX model is included as binary in the code itself. Ideally one would like being able to receive and update the model from the network. Bundling the model itself solves the previous issue
• Wasmtime parse f32 from u32, so the exec args must be unsigned 32bit in decimal base