FIX: Ensure topic user bookmarked synced on bookmark auto-delete (#10323)

For the following conditions, the TopicUser.bookmarked column was not updated correctly:

* When a bookmark was auto-deleted because the reminder was sent
* When a bookmark was auto-deleted because the owner of the bookmark replied to the topic

This adds another migration to fix the out-of-sync column and also some refactors to BookmarkManager to allow for more of these delete cases. BookmarkManager is used instead of directly destroying the bookmark in PostCreator and BookmarkReminderNotificationHandler.

db/migrate/20200728022830_sync_topic_user_bookmarked_column_with_bookmarks.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+class SyncTopicUserBookmarkedColumnWithBookmarks < ActiveRecord::Migration[6.0]
+  def up
+    should_be_bookmarked_sql = <<~SQL
+      UPDATE topic_users SET bookmarked = true WHERE id IN (
+        SELECT topic_users.id
+        FROM topic_users
+        INNER JOIN bookmarks ON bookmarks.user_id = topic_users.user_id AND
+          bookmarks.topic_id = topic_users.topic_id
+        WHERE NOT topic_users.bookmarked
+      ) AND NOT bookmarked
+    SQL
+    DB.exec(should_be_bookmarked_sql)
+
+    # post_action_type_id 1 is bookmark
+    should_not_be_bookmarked_sql = <<~SQL
+    UPDATE topic_users SET bookmarked = FALSE WHERE ID IN (
+      SELECT DISTINCT topic_users.id FROM topic_users
+      LEFT JOIN bookmarks ON bookmarks.topic_id = topic_users.topic_id AND bookmarks.user_id = topic_users.user_id
+      LEFT JOIN post_actions ON post_actions.user_id = topic_users.user_id AND post_actions.post_action_type_id = 1 AND post_actions.post_id IN (SELECT id FROM posts WHERE posts.topic_id = topic_users.topic_id) 
+      WHERE topic_users.bookmarked = true AND (bookmarks.id IS NULL AND post_actions.id IS NULL))
+    SQL
+    DB.exec(should_not_be_bookmarked_sql)
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end