Add Batch feature (XLS-56) (#5060)

- Specification: [XRPLF/XRPL-Standards 56](https://github.com/XRPLF/XRPL-Standards/blob/master/XLS-0056d-batch/README.md)
- Amendment: `Batch`
- Implements execution of multiple transactions within a single batch transaction with four execution modes: `tfAllOrNothing`, `tfOnlyOne`, `tfUntilFailure`, and `tfIndependent`.
- Enables atomic multi-party transactions where multiple accounts can participate in a single batch, with up to 8 inner transactions and 8 batch signers per batch transaction.
- Inner transactions use `tfInnerBatchTxn` flag with zero fees, no signature, and empty signing public key.
- Inner transactions are applied after the outer batch succeeds via the `applyBatchTransactions` function in apply.cpp.
- Network layer prevents relay of transactions with `tfInnerBatchTxn` flag - each peer applies inner transactions locally from the batch.
- Batch transactions are excluded from AccountDelegate permissions but inner transactions retain full delegation support.
- Metadata includes `ParentBatchID` linking inner transactions to their containing batch for traceability and auditing.
- Extended STTx with batch-specific signature verification methods and added protocol structures (`sfRawTransactions`, `sfBatchSigners`).

include/xrpl/protocol/STTx.h

@@ -125,10 +125,16 @@ public:
         @return `true` if valid signature. If invalid, the error message string.
     */
     enum class RequireFullyCanonicalSig : bool { no, yes };
+
     Expected<void, std::string>
     checkSign(RequireFullyCanonicalSig requireCanonicalSig, Rules const& rules)
         const;
 
+    Expected<void, std::string>
+    checkBatchSign(
+        RequireFullyCanonicalSig requireCanonicalSig,
+        Rules const& rules) const;
+
     // SQL Functions with metadata.
     static std::string const&
     getMetaSQLInsertReplaceHeader();
@@ -144,6 +150,9 @@ public:
         char status,
         std::string const& escapedMetaData) const;
 
+    std::vector<uint256>
+    getBatchTransactionIDs() const;
+
 private:
     Expected<void, std::string>
     checkSingleSign(RequireFullyCanonicalSig requireCanonicalSig) const;
@@ -153,12 +162,24 @@ private:
         RequireFullyCanonicalSig requireCanonicalSig,
         Rules const& rules) const;
 
+    Expected<void, std::string>
+    checkBatchSingleSign(
+        STObject const& batchSigner,
+        RequireFullyCanonicalSig requireCanonicalSig) const;
+
+    Expected<void, std::string>
+    checkBatchMultiSign(
+        STObject const& batchSigner,
+        RequireFullyCanonicalSig requireCanonicalSig,
+        Rules const& rules) const;
+
     STBase*
     copy(std::size_t n, void* buf) const override;
     STBase*
     move(std::size_t n, void* buf) override;
 
     friend class detail::STVar;
+    mutable std::vector<uint256> batch_txn_ids_;
 };
 
 bool