feat: add support for signed transactions with metadata in SmartTransactionsController

[nthpool]

• Introduced new types: SentinelMeta and SignedTransactionWithMetadata.
• Updated SmartTransactionsController to handle signed transactions with metadata.
• Enhanced tests to verify inclusion and omission of rawTxsWithMetadata in request body based on provided data.

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Note

Enables attaching metadata to submitted signed transactions and forwarding it to the backend.

• Updates SmartTransactionsController.submitSignedTransactions to accept signedTransactionsWithMetadata and include it in the POST body as rawTxsWithMetadata
• Introduces SentinelMeta and SignedTransactionWithMetadata types in types.ts and re-exports them from index.ts
• Extends tests to verify inclusion/omission of rawTxsWithMetadata and imports TransactionType for metadata

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