Add WASI support

[No9]

Given the separation we have between functions.rs and the build system it should be fairly trivial to output the executable as a WASI file.
The base rust image https://quay.io/repository/roche/alpine-libgcc would need to be updated to include the wasm32 target
rustup target add wasm32-wasi
and the build system would have to add cargo build --target wasm32-wasi to the cargo commands.
https://github.com/bytecodealliance/wasmtime/blob/main/docs/WASI-tutorial.md#from-rust

Rather than packaging to a runtime container https://github.com/roche-rs/roche/blob/main/src/template/Release.Dockerfile#L5
It might be better to wrap the outputs with an OCI https://github.com/engineerd/wasm-to-oci

And possibly utilised in something like https://github.com/deislabs/krustlet
It would be good to understand what the potential deployment targets are for a WASM service.
Research to be captured here.

[No9]

Cargo already has a fully integrated WASI stack https://github.com/bytecodealliance/cargo-wasi
Networking has yet to land in WASI WebAssembly/WASI#312
Minipot is a FreeBSD container platform based on Nomad that could target such an environment
https://github.com/pizzamig/minipot