Improve log to distinguish bootable-jar mode from server mode

[jmesnil]

With bootable jar mode (default):

[INFO] --- wildfly-jar-maven-plugin:6.0.0.Alpha1:package (default) @ helloworld-rs ---
[INFO] Provisioning server configuration based on the set of configured layers
[INFO] Building server based on [[wildfly@maven(org.jboss.universe:community-universe)#25.0.0.Beta1-SNAPSHOT inherit-packages=false inheritConfigs=false]] galleon feature-packs
[INFO] Found boot artifact org.wildfly.core:wildfly-jar-boot:jar:17.0.0.Beta1:provided in org.wildfly:wildfly-ee-galleon-pack:25.0.0.Beta1-SNAPSHOT
[INFO] CLI executions are done in forked process

With the <server> mode:

[INFO] --- wildfly-jar-maven-plugin:6.0.0.Alpha1:package (default) @ helloworld-rs ---
[INFO] Provisioning server configuration based on the set of configured layers
[INFO] Building server based on [[wildfly@maven(org.jboss.universe:community-universe)#25.0.0.Beta1-SNAPSHOT inherit-packages=false inheritConfigs=false]] galleon feature-packs
[INFO] CLI executions are done in forked process
...

From the logs, only the line Found boot artifact distinguishes the 2 modes. I think we should have the mode that is used displayed more proeminently in the logs.

When <cloud> is present, we have:

[INFO] Cloud support is enabled

We should add something similar when <server> is present:

[INFO] Server mode is enabled