Add user2 event to Xdump Option Builder

[paulcheeseman]

This patch updates the Xdump Option Builder to include the new user2 event which has been implemented in OpenJ9:

https://github.com/eclipse-openj9/openj9/issues/15636

Signed-off-by: Paul Cheeseman paul.cheeseman@uk.ibm.com

[pshipton]

jenkins website stage

[pshipton]

Can you squash the commits? We don't need both.

[pshipton]

Paul is having issues squashing, I'll just merge it as-is.