Makes KieSession implement the AutoCloseable interface, so it can be used in try-with-resources code blocks. No new tests added, because KieSession does not have any listener for dispose events. Therefore, some tests were changed to use try-with-resources to dispose the KieSession.
Fixes: https://github.com/apache/incubator-kie-issues/issues/1154
Makes KieSession implement the AutoCloseable interface, so it can be used in try-with-resources code blocks. No new tests added, because KieSession does not have any listener for dispose events. Therefore, some tests were changed to use try-with-resources to dispose the KieSession.