Add zinken testnet (#1741)

## Issue Addressed

- Resolves #1722

## Proposed Changes

This extends @danielschonfeld's work in #1739 with:

- Use an empty boot node list
- Remove the genesis state

## Additional Info

NA


Co-authored-by: Daniel Schonfeld <daniel@schonfeld.org>

common/eth2_config/src/lib.rs

@@ -111,6 +111,8 @@ define_net!(medalla, include_medalla_file, "medalla", true);
 
 define_net!(spadina, include_spadina_file, "spadina", true);
 
+define_net!(zinken, include_zinken_file, "zinken", false);
+
 #[cfg(test)]
 mod tests {
     use super::*;