StakeWise V2 Upgrade

Discussions about the snapshot are at https://forum.stakewise.io/t/554

Upgrade StakeWise smart contracts to the V2 release. The V2 features can be looked up at https://medium.com/@stakewise/a-new-era-for-stakewise-upgrading-to-a-decentralized-architecture-e598fde75ea8

The upgrade changes the implementation contracts for some of the existing contracts and initializes them:

Pool Contract

1. Pause contract
2. Change implementation address to 0xe68E649862F7036094f1E4eD5d69a738aCDE666f
3. Change Oracles address to 0x8a887282E67ff41d36C0b7537eAB035291461AcD by calling upgrade function
4. Change PoolValidators address to 0x002932e11E95DC84C17ed5f94a0439645D8a97BC by calling upgrade function
5. Unpause contract

RewardEthToken Contract

1. Pause contract
2. Change implementation address to 0x7cA75ccf264b2d9F91D4ABA7639fC7FcC73a7e09
3. Change Oracles address to 0x8a887282E67ff41d36C0b7537eAB035291461AcD by calling upgrade function
4. Unpause contract

MerkleDistributor Contract

1. Pause contract
2. Change implementation address to 0x1d873651c38D912c8A7E1eBfB013Aa96bE5AACBC
3. Change Oracles address to 0x8a887282E67ff41d36C0b7537eAB035291461AcD by calling upgrade function
4. Unpause contract