Refactor wth spread helper

[KevinBatdorf]

This refactors the wat style helpers so instead of

return new Uint8Array([
  ...header,
  ...typeSection,
  ...importSection,
  ...funcSection,
  ...memorySection,
  ...globalSection,
  ...exportSection,
  ...codeSection,
  ...dataSection,
]);

I can write this

return wat(
  header,
  typeSection,
  importSection,
  funcSection,
  memorySection,
  globalSection,
  exportSection,
  codeSection,
  dataSection,
);