implement volume mounts, env, and args

[bacongobbler]

The wasmtime provider allows volumes, environment variables, and function arguments to the main program. We have that available, but it's currently stubbed out/unused.

https://github.com/deislabs/krustlet-wasm3/blob/9f4faa34fdc77181df956864edc0c0600dc4d2d4/src/wasi_runtime.rs#L52-L58