feat(pebble): support pinning FormatMajorVersion (#10789)

* Upgrade to pebble v2.0.3

- Configure latest pebble database format at init
- Do not automatically ratchet database format if set in config
- Daemon messge about new available pebble format
- Document pebble config with formatMajorVersion
- Add warning to users running badger, nudging them to switch to flatfs or pebble
- docs: explain Pebble's `FormatMajorVersion`
- Use pebbleds instead of badgerds in t0060-daemon.sh
- Print badgerds warning message to stderr

Author: gammazero