Run DKG on contracts instead of Shuttermint

[jannikluhn]

Replace Shuttermint with a contracts based system.

• Remove all Shuttermint related code and DB tables.
• Sync DKG and ECIES key registration events (see Implement DKG contracts contracts#10)
• Send DKG and ECIES key registration transactions when needed
• Preserve the existing interface with the decryption key generation code
• Backwards compatibility is not required. Keypers will not update their existing setups but deploy new ones
• Reorg safety is not required yet
• Update the mise test setup
• Add end to end tests