mgmt: use a separate validator for prefix announcements

This commit also configures the default prefix_announcement_validation
section in nfd.conf.sample to accept any prefix announcement.

refs: #5031
Change-Id: I82e34ce783dfe77c170dd02e78a4bc86faa0147a
diff --git a/daemon/mgmt/rib-manager.hpp b/daemon/mgmt/rib-manager.hpp
index 1be0b81..51f9dfc 100644
--- a/daemon/mgmt/rib-manager.hpp
+++ b/daemon/mgmt/rib-manager.hpp
@@ -72,6 +72,12 @@
   disableLocalhop();
 
   /**
+   * @brief Apply prefix_announcement_validation configuration.
+   */
+  void
+  applyPaConfig(const ConfigSection& section, const std::string& filename);
+
+  /**
    * @brief Start accepting commands and dataset requests.
    */
   void
@@ -245,6 +251,7 @@
   ndn::nfd::FaceMonitor m_faceMonitor;
   ndn::ValidatorConfig m_localhostValidator;
   ndn::ValidatorConfig m_localhopValidator;
+  ndn::ValidatorConfig m_paValidator;
   bool m_isLocalhopEnabled;
 
   scheduler::ScopedEventId m_activeFaceFetchEvent;