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/STParsedJSON.cpp

@@ -27,6 +27,7 @@
 #include <xrpl/protocol/AccountID.h>
 #include <xrpl/protocol/ErrorCodes.h>
 #include <xrpl/protocol/LedgerFormats.h>
+#include <xrpl/protocol/Permissions.h>
 #include <xrpl/protocol/SField.h>
 #include <xrpl/protocol/STAccount.h>
 #include <xrpl/protocol/STAmount.h>
@@ -373,10 +374,35 @@ parseLeaf(
             {
                 if (value.isString())
                 {
-                    ret = detail::make_stvar<STUInt32>(
-                        field,
-                        beast::lexicalCastThrow<std::uint32_t>(
-                            value.asString()));
+                    if (field == sfPermissionValue)
+                    {
+                        std::string const strValue = value.asString();
+                        auto const granularPermission =
+                            Permission::getInstance().getGranularValue(
+                                strValue);
+                        if (granularPermission)
+                        {
+                            ret = detail::make_stvar<STUInt32>(
+                                field, *granularPermission);
+                        }
+                        else
+                        {
+                            auto const& txType =
+                                TxFormats::getInstance().findTypeByName(
+                                    strValue);
+                            ret = detail::make_stvar<STUInt32>(
+                                field,
+                                Permission::getInstance().txToPermissionType(
+                                    txType));
+                        }
+                    }
+                    else
+                    {
+                        ret = detail::make_stvar<STUInt32>(
+                            field,
+                            beast::lexicalCastThrow<std::uint32_t>(
+                                value.asString()));
+                    }
                 }
                 else if (value.isInt())
                 {