Fix #220: When generating a new project, restx-server-jetty dependenc…

…y should be considered optional in order :

- To be able ot use it at compile time (particularly in AppServer)
- To be able to have IDE like IntelliJ to provide jetty libs to classpath when running AppServer
- To be able to not package it (nor its dependencies) when building the war
Note that by removing restx-server-jetty from packaged libs, we need to bring back restx-servlet artefact (which was initially pulled from restx-server-jetty)
directly at the dependency root level, in order to have it packaged into the war (otherwise, we wouldn't be able to use
restx servlet-specific stuff when deploying on standard servlet containers such as tomcat)

restx-core-shell/src/main/resources/templates/srv/main/_md.restx.json

@@ -33,7 +33,8 @@
 {{#includeStatsModule}}
             "io.restx:restx-stats-admin:${restx.version}",
 {{/includeStatsModule}}
-            "io.restx:restx-server-jetty:${restx.version}",
+            "io.restx:restx-servlet:${restx.version}",
+            "io.restx:restx-server-jetty:${restx.version}!optional",
             "io.restx:restx-apidocs:${restx.version}",
             "io.restx:restx-specs-admin:${restx.version}",
             "io.restx:restx-admin:${restx.version}",