[Light Client] Update light client contract to support epoch

[mrain]

Epoch logic is removed from light client contract in #1939
Now the contract sticks with the genesis stake table.
We should change the existing API or add a new API to update the stake table when the epoch advances.

[alxiong]

Subtasks:

• update light client signing code to sign over not just LightClientState (3 fields: view_num, block_height, block_comm_root), but LightClientState || StakeTableState.
  • this also requires being epoch-aware and fetching proper next stake table commitment logic
• update hotshot-state-prover's circuit and prover service apis to take in extra next_stake_table_comm variables
• regenerate LightClientStateUpdateVK.sol
• update PlonkVerifier.sol to accept an modified public input (from current 7 fields, to 11 fields)
  • note: reason we didn't define PI' = H(PI) s.t. the public input is always a single field, is due to choice of H. Rescue hash in solidity is expensive, and we don't have keccak256 gadget in jellyfish.
• update LightClient.sol to enforce last block of every epoch has an update before moving forward