rdbms: allow automatic PDO creation of SQLite database files

rdbms: allow automatic PDO creation of SQLite database files

Define missing DatabaseSqlite::doSelectDomain() method to handle attempts
to change the database, prefix, and/or schema.

Also add sanity check to serverIsReadOnly() to make sure open() was called

Change-Id: I72c25bf4dab5e01def3fb9472217e7637aede1d4