cmd: add flags for withdrawal address and network

[xenowits]

Problem to be solved

• Add following flags to charon create cluster command:
  • -withdrawal-address
    • Must verify it's a 42 char string like ^0x()*40 or however the appropriate regex works. Basically the exact same as dkg-poc approach to verification (including checksum if address is mixed case, warn if non-checksummed address). See this.
    • For verify an address, we can use this verification.
    • We can make this a required flag, no defaults. OR,
    • We can make a zero address default withdrawal credential. In that case, remove both gnosis and mainnet from the network options.
  • --network: any network from this list [mainnet, prater, kintsugi, kiln, gnosis]

Proposed solution

Refactor cmd.runCreateCluster to include these flags.