Ignore errors from lastInsertId()

lastInsertId() fails if the DB structure does not match Db module's assumption, for example, a table without tablename_id_seq sequence in PostgreSQL.

I agree with the opinion in #989, Db module is to be simple.
However, it is better to avoid causing error even if the database structure is unexpected.
So I suggest to ignore the exception for uncommon conditions.

This provides the same behavior as other RDBMS like MySQL for PostgreSQL.
I think this is good meeting ground between simplicity and stability.
Technically possible, of course, but I have anxiety.
It changes the protocol of `Driver¥Db` class.
If programs expect it to throw exceptions when `lastInsertId()` fails to find an id, they may misbehave.
I mean it lose compatibility if external programs uses Db drivers.
I am not sure how critical this problem is.

I checked current implementation again and found Db module caught `PDOException`.
https://github.com/Codeception/Codeception/blob/2.0/src/Codeception/Module/Db.php#L124
I think both of your suggestions are better than my way, but catching `PDOException` seems to be better than the latter in point of consistency.

I also checked driver initialization and all drivers' implementation then found drivers that Db module uses are guaranteed to use PDO.
Therefore my previous post was misunderstanding and it is completely correct to catch only `PDOException`.

I want to add a patch to limit exceptions to `PDOException` if you are ok.
Any advices are welcome. Thanks!