Add "releaseAfterClose" option to the nexus-staging-maven-plugin

It will help our CLM evaluations/deployments a lot if we can add a mode to the nexus-staging-maven-plugin where we immediately release a staging repository if it has been successfully closed. This is because a lot of end users don't want real staging, they just want their deployed artifacts scanned by CLM.

This is possible with the current plugin, but the configuration is quite complex.

I propose doing this with a "releaseAfterClose" flag. The default value for this will be false.