use maven 3 for jackpot30

[ebarboni]

trying to upgrade the pom and the plugin to mach maven 3. (A bit like in nbm-maven-plugin)

• using annotation instead of javadoc tag
• compiling on java 17 (version 28 has 61.0 class file => 17)
• using configuration parameter for the configuration file instead Xpp3Dom for the plugin parameter
  but keep xpp3 for reading the compiler plugin configuration

a bit of reformat using NetBeans

[mbien]

not tested but the update looks good

[lahodaj]

Thanks!

[ebarboni]

sidenote, showgui goal is not working because the cli argument --show-gui is no more an option available (maybe a bug, or an history change)