Retrieves an existing cryptocurrency wallet address for the beneficiary on the specified blockchain network, or automatically creates a new wallet if none exists. Each beneficiary can have multiple wallets (one per blockchain network). The wallet address can be used to receive cryptocurrency deposits. Supported networks include Ethereum (ETH), Polygon, Tron (TRX), Stellar (XLM), Base, and Solana. The wallet is managed by Caliza, so users don't need to manage private keys.