Clean up org.jboss.logmanager.ext handling in the EAP CD vs 7.0/7.1 images

Currently EAP CD is using the org.jboss.logmanager.ext stuff from os-eap7-modules and os-eap7-launch (see json-logging.sh). This is problematic because the module that's being created is:

1) Using an archive that was built a different logmanager version than we ship in EAP CD. Different major version even. So this is fragile and can break at any time.
2) Pulls in javax.json as a module resource, even though CD 12 ships it. To an extent that might be better than depending on the module we ship though, as the pulled in resource may better match what the logmanager.ext jar was compiled against. But anyway it needs thought.

Furthermore, with WFCORE-2951 a native variant of this functionality may be available. But there may be subtle differences in the native behavior that we need to account for.

Note that the https://github.com/jboss-openshift/cct_module/blob/master/os-eap7-launch/added/launch/json_logging.sh behavior might end up being just fine. It checks for env var ENABLE_JSON_LOGGING and if present turns on the formatter named "OPENSHIFT". That seems like something that would not have to change even if the details of the config of the OPENSHIFT formatter or the module behind it do change.

Note that in the issue title I mention "EAP 7.0" images. If we no longer produce such things, that can be part of the fix; e.g. moving legacy things from os-eap7-modules to os-eap71-modules.