java-openliberty: In template(s) use property to reference app name from server.xml config

[scottkurz]

Instead of:

<webApplication location="starter-app.war" contextRoot="/"/>

in templates/default/src/main/liberty/config/server.xml we should be referencing the artifactId or the finalName which is I think what the MP starter does: (https://github.com/eclipse/microprofile-starter)