Speed up connection creation on 9.0+

After startup the JDBC driver checks the server version and if it's 9.0+ it sets the `extra_float_digits` and optionally the `application_name`. Setting each of these requires a couple of round trips as each is executed in its own `SET foo = 'bar'` statement.

If you know the remote server is 9.0+ then you can instead send both properties in the StartupMessage itself.

This patch adds a property to instruct the driver that the server you are connecting to is a "modern server", i.e. 9.0+. For lack of a better name I've called the property `isModernServer`. If set to "true" then it will assume the remote server is 9.0+ and set the properties in the StartupMessage. Otherwise it'll function as it has in the past.