Solana Improvement Iteration 1

[lumtis]

This EPIC lists issues to prioritize as a next iteration for improving the integration:

EPIC can eventually be renamed if we find a more descriptive name of the overall purpose.

• More reliability/testing
• Better DevEx
• Eventual issues from audit and testnet testing

### Tasks
- [ ] https://github.com/zeta-chain/node/issues/2604
- [ ] https://github.com/zeta-chain/protocol-contracts-solana/issues/19
- [ ] https://github.com/zeta-chain/protocol-contracts-solana/issues/18
- [ ] https://github.com/zeta-chain/node/issues/2747