PDO\SQLite: Add support for getting raw SQL query (same as SQLite3::getSQL)

### Description

SQLite3 class supports fetching the raw SQL query as a string from the statement:

`SQLite3Stmt::getSQL(bool $expand = false)`

Adding an attribute to fetch the same for PDO\SQLite would be nice, eg.:

```
PDOStatement::getAttribute(PDO\SQLite::ATTR_SQL_STATEMENT)
PDOStatement::getAttribute(PDO\SQLite::ATTR_SQL_EXPANDED_STATEMENT)
```