Simplify identity generation

[DavideD]

JDBC can generate an identity using different strategies. One can tell Hibernate ORM which one to choose using hibernate.jdbc.use_get_generated_keys. Currently, we are trying to support all the queries generated by Hibernate ORM for the different cases.

With the Vert.x client, we usually have one way to get the id, so we can ignore the property and select the best option for each database.

[DavideD]

Done

[DavideD]

We are using the query generated when the property is set to false.
We are having a couple of issues with the queries generated by ORM that we will need to investigate if we want to remove the additional operations we do on the generated queries here.

Some of the related issues we've created on ORM:

• SqlServer: https://hibernate.atlassian.net/browse/HHH-16365
• Oracle: https://hibernate.atlassian.net/browse/HHH-16418