CASSGO-7 Change Batch API to be consistent with Query()

[Zariel]

Make Batch behave the same way as Query so it looks like

session.Batch().Query("SELECT * FROM table").Query("SELECT * FROM table").Exec()

This means renaming session.NewBatch -> Batch and removing session.ExecuteBatch

[OleksiienkoMykyta]

Currently, it's marked as deprecated to keep backward compatibility in the merged PR(#1764), but generally, we don't use it anymore.
Solved. The issue should be closed.

[joao-r-reis]

Hmm so session.ExecuteBatch() still exists and it is not marked as deprecated.

I've created CASSGO-57 to deprecate it and CASSGO-58 to remove it in the future.

This current issue (#1187 CASSGO-7) has been resolved already so closing this.