milestone: run a "hello world" wasm

[hawkw]

• we should be able to run a wasm that basically invokes __wasi_fd_write to stdout with the string "hello world".
• i don't care about anything else working
• it's okay if the wasm is interpreted
• we can just include it in the kernel image for now (rather than figuring out "fs")

[hawkw]

cc @iximeow

[mystor]

Resolved by #58