Adds required extension points for debugger and editor plugins.

[DaanVanYperen]

Required extension points for debugger and editors plugins.

• New (package local) extension point for debuggers and editors. (InternalFactory). Can be set in plugins via WorldConfigurationBuilder.
• New lifecycle phase listener for debuggers and editors (ArtemisPhaseListener). Captures pre/post init, pre/post destroy.
• Removes final from impl specific classes to make the debug plugin work as-is. Keeps them package local.
• Makes some small changes to managers to make it easier to replace ComponentMapper creation via ComponentManager inheritance.

The #570 Grafting mechanic is planned to replace (part of?) the InternalFactory, I'd like to retain some of the small changes and the phase listener as we probably don't want to graft world itself.

@junkdog perhaps put the grafting in this branch?

[DaanVanYperen]

Missing ingredients:

• Lifecycle plugin: https://github.com/DaanVanYperen/artemis-odb-contrib/blob/develop/contrib-plugin-lifecycle-listener/src/main/java/com/artemis/LifecycleListenerPlugin.java
• Debug plugin: https://github.com/DaanVanYperen/artemis-odb-contrib/blob/develop/contrib-plugin-debug/src/main/java/net/mostlyoriginal/plugin/DebugPlugin.java
• Grafting (alternative way to do the InternalFactory).

[DaanVanYperen]

Solved using Graftt. Compromise is JVM targets only, but can live with that.