Support a Galleon feature pack to install Keycloak adapters

In conjunction with the bootable jar support currently being developed this feature request is to cover support for Keycloak client side adapter installation integrated with the Elytron security subsystem.

The main feature pack is anticipated to be delivered by the Keycloak project, however as this is specifically for use with WildFly we likely need WildFly documentation and possibly test cases so this Jira issue to to cover tasks required within WildFly.