Add support for Go

[taybenlor]

There's two pathways that seem viable here:

1. Build tinygo and throw it up on WAPM. tinygo appears to already have WASI support but I can't confirm whether the compiler itself can be built for WASI. This would fit into the current execution model best.

2. Build go itself (https://golang.org/doc/install/source) using $GOOS=js and $GOARCH=wasm. This builds Go in a way that is only compatible with its own wasm_exec JS runtime (https://github.com/golang/go/wiki/WebAssembly). So we'd need to add a new system for running Go code to Runno (basically an alternative to the WASI system).

The first seems like the best option since it doesn't require changing much of the architecture of Runno.

[taybenlor]

It looks like tinygo is very dependent on LLVM and Go themselves to build. This makes me think it's going to be quite challenging to build tinygo to WASM without knowing it very well.