Add PermissionDelegation feature (#5354)

This change implements the account permission delegation described in XLS-75d, see https://github.com/XRPLF/XRPL-Standards/pull/257.

* Introduces transaction-level and granular permissions that can be delegated to other accounts.
* Adds `DelegateSet` transaction to grant specified permissions to another account.
* Adds `ltDelegate` ledger object to maintain the permission list for delegating/delegated account pair.
* Adds an optional `Delegate` field in common fields, allowing a delegated account to send transactions on behalf of the delegating account within the granted permission scope. The `Account` field remains the delegating account; the `Delegate` field specifies the delegated account. The transaction is signed by the delegated account.

src/libxrpl/protocol/ErrorCodes.cpp

@@ -107,6 +107,7 @@ constexpr static ErrorInfo unorderedErrorInfos[]{
     {rpcSRC_ACT_MALFORMED,      "srcActMalformed",      "Source account is malformed.", 400},
     {rpcSRC_ACT_MISSING,        "srcActMissing",        "Source account not provided.", 400},
     {rpcSRC_ACT_NOT_FOUND,      "srcActNotFound",       "Source account not found.", 404},
+    {rpcDELEGATE_ACT_NOT_FOUND, "delegateActNotFound",  "Delegate account not found.", 404},
     {rpcSRC_CUR_MALFORMED,      "srcCurMalformed",      "Source currency is malformed.", 400},
     {rpcSRC_ISR_MALFORMED,      "srcIsrMalformed",      "Source issuer is malformed.", 400},
     {rpcSTREAM_MALFORMED,       "malformedStream",      "Stream malformed.", 400},