[ticket/16741] Specific DBs fixes

MSSQL:
- Fix bool type
- Fix comparator
- Drop Default constraint before deleting column
- Rename Default constraint to use phpBB's names
- Re-create the indices when changing the type of one column
- Uses varchar instead of varbinary

PostgreSQL:
- Creates auto increment sequences by hand instead of using serial
  in order to use phpBB's names
- Drop constraint on unique / primary indices

Oracle:
- Rename indices to use phpBB's names
- Fix string not null behaviour
- Fix broken regex in Oracle driver
- Handle to long indices on Oracle
- Rename auto_increment trigger and sequence
- Automatically lowercase keys in assoc results

PHPBB3-16741

phpBB/config/default/container/services_db.yml

@@ -10,7 +10,7 @@ services:
     dbal.conn.doctrine:
         synthetic: true
 
-    # ----- DB Tools -----
+# ----- DB Tools -----
     dbal.tools.factory:
         class: phpbb\db\tools\factory