feat: add EthereumEipXXXXTransaction support

[Dosik13]

Description:

Add native construction and signing of Ethereum transaction data for all four formats (Legacy, EIP-2930, EIP-1559, EIP-7702), so a developer can build and sign an Ethereum transaction inside the SDK and submit it through the existing EthereumTransaction. Implements the cross-SDK proposal in sdk-collaboration-hub.

• Add EthereumTransactionBody interface (Sign, ToBytes, String) implemented by the Legacy, EIP-2930, EIP-1559, and EIP-7702 transaction types
• Add native Sign(key) to each transaction type — secp256k1 signing with recovery-id computation, writing R/S and V/RecoveryId back onto the receiver and returning the signed RLP; reject non-ECDSA keys
• Extract shared _signTypedTransaction and _encodeTypedWithSignature helpers for the typed variants, and split serialization into _toUnsignedRLP / _encodeWithSignature
• Add paired typed and raw-bytes accessors for every field across all four types (GetValue/SetValue and GetValueBytes/SetValueBytes)
• Add Ethereum RLP canonical integer encoding helpers (uint64/big.Int to minimal big-endian, zero as empty bytes)
• Add structured AccessListItem type with getters/setters, AddStorageKey, and RLP helpers; expose it through GetAccessListItems/SetAccessListItems/AddAccessListItem
• Replace the positional AuthorizationTuple [6][]byte with a structured Authorization type (chainId, address, nonce, yParity, r, s) with constructor, accessors, String, and RLP helpers
• Add EthereumTransaction.SetEthereumDataFromBody(body) to serialize a signed transaction body directly, returning an error rather than submit an unsigned transaction
• Add EthereumTransactionData wrapper dispatch over the four types (FromBytes, ToBytes, Sign, GetTransaction, GetData/SetData)
• Add unit tests covering signing, RLP round-trips, accessors, access lists, authorization lists, and decode error paths

Related issue(s):

Fixes #1742

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[lfdt-bot]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

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[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 66 complexity · 0 duplication

Metric	Results
Complexity	66
Duplication	0

View in Codacy

_{TIP This summary will be updated as you push new changes. Give us feedback}

[codecov]

Codecov Report

❌ Patch coverage is 96.01911% with 25 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
sdk/ethereum_transaction_data.go	87.30%	5 Missing and 3 partials ⚠️
sdk/ethereum_eip1559_transaction.go	95.23%	2 Missing and 3 partials ⚠️
sdk/access_list_item.go	92.98%	2 Missing and 2 partials ⚠️
sdk/ethereum_legacy_transaction.go	95.18%	2 Missing and 2 partials ⚠️
sdk/ethereum_eip7702_transaction.go	98.37%	1 Missing and 1 partial ⚠️
sdk/ethereum_transaction.go	81.81%	1 Missing and 1 partial ⚠️

Files with missing lines	Coverage Δ
sdk/authorization.go	100.00% <100.00%> (ø)
sdk/ethereum_eip2930_transaction.go	95.15% <100.00%> (+34.62%)	⬆️
sdk/ethereum_encoding.go	100.00% <100.00%> (ø)
sdk/ethereum_eip7702_transaction.go	92.19% <98.37%> (+92.19%)	⬆️
sdk/ethereum_transaction.go	88.88% <81.81%> (-1.12%)	⬇️
sdk/access_list_item.go	92.98% <92.98%> (ø)
sdk/ethereum_legacy_transaction.go	95.58% <95.18%> (+95.58%)	⬆️
sdk/ethereum_eip1559_transaction.go	94.94% <95.23%> (+33.69%)	⬆️
sdk/ethereum_transaction_data.go	88.52% <87.30%> (+49.54%)	⬆️

... and 30 files with indirect coverage changes

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