Deno support

Deno support was discussed in https://github.com/pyodide/pyodide/issues/1477#issuecomment-821942072 and I think it would be good to add it and have some minimal tests in CI. As discussed in the linked PR only a few minor fixes are needed. I'll open a PR shortly.

Personally, the use case I'm interested in that could benefit from running in Deno is server side sandboxing https://github.com/pyodide/pyodide/issues/869#issuecomment-1268006881

What's left is:

- [ ] Support running in Deno https://github.com/pyodide/pyodide/pull/3421
- [ ] Adapt `src/js/streams.ts` for Deno
- [ ] Add support for deno runtime to `pytest-pyodide`
- [ ] Add some tests with Deno in CI
- [ ] Update documentation
- [ ] (optional) Make deno work with local file (without network access) if possible for sandboxing