Staking API (2024-05-03)

🛠️ We've updated the endpoint description for clarity:

• [Ethereum] Updated the description of unsigned_transaction in response to the Ethereum POST /stake-intents endpoint.
• See more in the Post Stake Intent API doc.
• [Solana] Added on-chain status to the GET /solana/{network}/stake-accounts endpoint.
• See more in the Get Stake Accounts API doc.