add missing types for safe page moving from opportunity to initiatives (#4374)

network-api/networkapi/wagtailpages/pagemodels/base.py

@@ -86,6 +86,12 @@ class InitiativesPage(PrimaryPage):
         'MiniSiteNameSpace',
         'OpportunityPage',
         'RedirectingPage',
+        # The following additional types are here to ensure
+        # that the /initiatives route can house all the pages
+        # that originally lived under /opportunity
+        'BlogPage',
+        'CampaignPage',
+        'YoutubeRegretsPage',
     ]
 
     primaryHero = models.ForeignKey(