Restrict 'cd' to the 'prepare' context

The change follows up the previous fix, which blocked 'cd' command in 'prepare' context entirely.

Bug: https://tree.taiga.io/project/jktjkt-netconf-cli/issue/223
Fixes: 218ee7bcbef1c066a2be56f087ab8c824b529188
Change-Id: Iea0902e7981bcf3f9d41425e58cdd64ef6ea0be0
diff --git a/src/interpreter.hpp b/src/interpreter.hpp
index f2cfd11..3723432 100644
--- a/src/interpreter.hpp
+++ b/src/interpreter.hpp
@@ -36,6 +36,8 @@
     void operator()(const quit_&) const;
 
 private:
+    void checkRpcPath(const dataPath_& commandPath) const;
+
     [[nodiscard]] std::string buildTypeInfo(const std::string& path) const;
 
     template <typename PathType>