Make implementing the org.wildfly.extension.elytron.Configurable optional for configurable components.

Presently custom components within the Elytron subsystem are required to implement the 'org.wildfly.extension.elytron.Configurable' interface if they wish to support receiving a Map of configuration Strings.

This means that the custom component needs to depend on both the WildFly Elytron project and the subsystem.

It should be possible for components to add the following method without implementing the interface and be configurable.

void initialize(final Map<String, String> configuration);

We also have a long standing issue in that if we add a new component to WildFly Elytron it can not be used until we can add a resource to configure it. By supporting configurable custom components without needing a dependency on the subsystem new components added to WildFly Elytron could be usable whilst the subsystem definitions catch up.