Allow disabling IPv6 for emulators (e.g. for Codespaces port forwarding)

### Environment info

**firebase-tools:** 9.16.6

**Platform:** Linux
### Test case

Install firebase-tools.

### Steps to reproduce

Run the firebase emulators with `npx firebase emulators:start`

### Expected behavior

All services would bind to `127.0.0.1` (and, optionally, also to `[::ffff:127.0.0.1]`).
The [codespaces port forwarding feature](https://docs.github.com/en/codespaces/developing-in-codespaces/forwarding-ports-in-your-codespace) would work as expected.

### Actual behavior

Some services (in particular the firestore emulator) only bind to IPV6 localhost:

```
State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
LISTEN 0 4096 [::ffff:127.0.0.1]:43299 *:* users:(("java",pid=19991,fd=78))
LISTEN 0 4096 [::ffff:127.0.0.1]:8080 *:* users:(("java",pid=19991,fd=79))
LISTEN 0 50 [::ffff:127.0.0.1]:36567 *:* users:(("java",pid=19991,fd=22))
LISTEN 0 4096 [::ffff:127.0.0.1]:34265 *:* users:(("java",pid=19991,fd=53))
```

and the codespaces port forwarding is not working.