We show `realm_empty_topic_display_name` for empty string
topics in the SETTINGS/TOPICS table.
This commit makes it possible for users to search for
the `realm_empty_topic_display_name` value to filter out empty
string topics.
This commit adds support to display `realm_empty_topic_display_name`
value in the SETTINGS/TOPICS table for topics having the actual
value of empty string.