RPC Sign method : Add a description to explain the purpose of signing transactions

[redDwarf03]

Is your feature request related to a problem?

No response

Describe the solution you'd like

Add in the sign request object a description

{
  "serviceName": String,              // Service name to use to sign the tx
  "pathSuffix": String,               // Additional information to add to a service derivation path (optional)
  "description": String {             // Readable description to explain the purpose of signing transactions (locale + description)
    "en": "Readable description in English",
    "fr": "Description lisible en français",
  },
  "transactions": [
    {
      "type": String,                 // Type of transaction
      "version": Number,              // Version of the transaction (used for backward compatiblity)
      "data": Object                  // Transaction data zone (identity, keychain, smart contract, etc.)
    }
  ]
}

Additional context

https://github.com/archethic-foundation/archethic-wallet-client-dart/issues/40

Epic

No response