Prevent example modules from being published to Maven Central

[bdemers]

What

Introduce an intermediate parent POM at scim-server-examples/pom.xml (groupId org.apache.directory.scimple.examples, packaging=pom) that makes the example modules non-publishing, and reparent the six examples under it.

Why

The scim-server-examples/* demos are intentionally not production-hardened (cleartext passwords, no auth/TLS). They are documented as out of scope and "not published to Maven Central", but nothing in the build actually enforced that — a full reactor deploy would have staged them. This makes that guarantee structural rather than aspirational.

How

• New scim-server-examples/pom.xml sets maven.deploy.skip and skipNexusStagingDeployMojo once, plus an apache-release profile that skips the source, gpg, and javadoc plugins for the examples.
• The six example modules inherit from it, so future example modules are non-publishing by default.
• The root reactor now lists the single scim-server-examples aggregator instead of the six individual modules.
• scim-coverage is deliberately left untouched. It is the last reactor module, which is where nexus-staging-maven-plugin triggers the deferred batch upload — skipping it would suppress publishing of the real libraries. A comment marks it as required-last.

The set of published modules (scim-spec-schema, scim-spec-protocol, scim-client, scim-core, scim-server, scim-spring-boot-starter, and the test-support artifacts) is unchanged.

Verification

Local, -Pci:

• ./mvnw -Pci -DskipTests verify — BUILD SUCCESS across all modules (RAT + SpotBugs clean).
• During a full-reactor deploy, each of the six examples logs Skipping Nexus Staging Deploy Mojo at user's demand., while scim-core and scim-server perform deferred deploys — confirming the skip does not leak to the published libraries.

Note: a local file-repo deploy cannot exercise the real Nexus staging path (nexus-staging with extensions=true ignores -DaltDeploymentRepository and contacts repository.apache.org at reactor close). A maintainer with ASF staging credentials should confirm a real staging run shows the examples absent and the libraries present before the next release.