feat(sdk-coin-vet): add transaction builder logic for vechain

[at31416]

This pull request introduces significant updates to the VeChain (VET) SDK module, including dependency additions, interface enhancements, and substantial refactoring of the transaction handling logic. These changes aim to improve the SDK's functionality, maintainability, and support for VeChain-specific features.

Dependency Updates:

• Added @vechain/sdk-core and @vechain/sdk-network as new dependencies in package.json to support VeChain-specific transaction and network capabilities.

Interface and Type Enhancements:

• Introduced VetTransactionExplanation interface in iface.ts to extend the base transaction explanation with VeChain-specific fields like sender and transaction type.
• Added ExplainTransactionOptions and VetParseTransactionOptions in types.ts to define options for transaction explanation and parsing.

Refactoring of Transaction Handling:

• Reorganized transaction-related files into subdirectories (transaction/transaction, transactionBuilder/transactionBuilder, etc.) for better structure and modularity.
• Replaced the old Transaction and TransactionBuilder implementations with new classes that leverage @vechain/sdk-core for VeChain-specific functionality, including support for transaction clauses, sender signatures, and fee payer signatures. [1] [2] [3]
• Added a TransferBuilder class to handle native VET transfers, ensuring validation of transaction clauses and recipient details. [1] [2]

TransactionBuilderFactory Enhancements:

• Updated TransactionBuilderFactory to support deserialization of signed transactions and initialization of builders with VeChain-specific logic.

VeChain Coin Implementation (Vet class):

• Implemented verifyTransaction, parseTransaction, and explainTransaction methods to validate, parse, and explain transactions, including checks for recipient and output consistency. [1] [2]
• Added support for rebuilding transactions using the new transaction builder factory.

These changes collectively enhance the SDK's capabilities for working with VeChain transactions while improving code organization and maintainability.Ticket: COIN-4379