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/STInteger.cpp

@@ -22,6 +22,7 @@
 #include <xrpl/beast/utility/instrumentation.h>
 #include <xrpl/json/json_value.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/Permissions.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STBase.h>
 #include <xrpl/protocol/STInteger.h>
@@ -177,6 +178,27 @@ template <>
 Json::Value
 STUInt32::getJson(JsonOptions) const
 {
+    if (getFName() == sfPermissionValue)
+    {
+        auto const permissionValue =
+            static_cast<GranularPermissionType>(value_);
+        auto const granular =
+            Permission::getInstance().getGranularName(permissionValue);
+
+        if (granular)
+        {
+            return *granular;
+        }
+        else
+        {
+            auto const txType =
+                Permission::getInstance().permissionToTxType(value_);
+            auto item = TxFormats::getInstance().findByType(txType);
+            if (item != nullptr)
+                return item->getName();
+        }
+    }
+
     return value_;
 }