Add abilityto add oneself to lists (#12271)

* Add ability to add oneself to lists

* Change search results to include oneself when searching through followers

* Mark follow relation as optional in ListAccount

app/models/account.rb

@@ -429,6 +429,8 @@ class Account < ApplicationRecord
             SELECT target_account_id
             FROM follows
             WHERE account_id = ?
+            UNION ALL
+            SELECT ?
           )
           SELECT
             accounts.*,
@@ -444,7 +446,7 @@ class Account < ApplicationRecord
           LIMIT ? OFFSET ?
         SQL
 
-        records = find_by_sql([sql, account.id, account.id, account.id, limit, offset])
+        records = find_by_sql([sql, account.id, account.id, account.id, account.id, limit, offset])
       else
         sql = <<-SQL.squish
           SELECT