Initialize contract v2 environment and specs

[lumtis]

This epic groups tasks toward the goal of:

• Having first usable implementation of v2 contracts
• Completing specs
• Having a usable environment to start experimenting applications
• Having CI initialize with Solidity dev best practices (Slither, Fuzzing, Coverage)

### Tasks
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/165
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/174
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/180
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/189
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/192
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/193
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/194
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/195
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/196
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/197
- [ ] https://github.com/zeta-chain/protocol-contracts/issues/255

[lumtis]

All issues completed