config: update native implementation in genesis config

Update GovernanceProxyAdmin, Governance, Policy and GovernanceReward
implementation bytecodes.

Update Policy genesis allocations:
  * increase baseFee and minGasTip to 20 Gwei
  * add candidateLimit storage item

Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>

Author: AnnaShaleva