Add data field to legacy transaction

[PiVortex]

The legacy transaction type for EVM does not support the data field - it should

https://github.com/NearDeFi/chainsig.js/blob/main/src/chain-adapters/EVM/types.ts#L22

Rather than having different methods for legacy and different EIPs, we can change EVMUnsignedTransaction to be any one of TransactionRequest instead of a specific one.

https://github.com/NearDeFi/chainsig.js/blob/main/src/chain-adapters/EVM/types.ts#L10
https://github.com/wevm/viem/blob/3bc5e6f3c4a317441063342dd9ec2aaa7eb56b01/src/types/transaction.ts#L287

As such LegacyTransaction methods can be removed.

Since removing LegacyTransaction will add a breaking change I would suggest for now adding support for all transaction types to EVMUnsignedTransaction and later removing LegacyTransaction along with other breaking changes