feat(crypto): mnemonic generation/encryption/decryption/storage (#2014)

Introduce Wallet Name and Password for Enhanced Seed Management

This commit introduces a new optional parameter, `wallet_name`, to the mm2 configuration. This parameter, along with `wallet_password`, allows for enhanced seed management by MM2, reducing the need for GUIs to handle seed management. 

If `wallet_name` and `wallet_password` are provided, MM2 will handle the generation, encryption, and storage of the wallet's seed. If a `passphrase` is also provided, it will be used as the seed and then encrypted and stored. If no `passphrase` is provided, MM2 will generate a new seed, encrypt it, and store it. 

This commit also introduces a new API method `get_mnemonic` that allows for the retrieval of the wallet's seed, either in encrypted or plaintext format, depending on the provided parameters.

This change enhances the security and flexibility of seed management in MM2, allowing for different modes of operation depending on the user's needs.