Attach the PathManager to the deployment unit
[WFCORE-452] Wire extension resources into host model

This is needed since in order to configure subsystems on a host the
extensions from the domain model have not yet been initialised.
Some logic to make sure that defining extensions in both the domain and
host model is not an error, and to make sure that only the last remove
from the model does the actual removal from the registry.
[WFCORE-452] Share XMLMapper and subsystem writer registry between host and domain

parsers.

Also clean the extension registry properly on reload.
[WFCORE-452] Ugly Hack! Allow turning off looking for profile resource for tests of type HC

Hope to be able to remove this later
[WFCORE-452] Register profile resource definition in domain model, as part of host model

init so extensions get properly registered at host boot.
[WFCORE-452] Add support for SubsystemRegistration.setHostCapable()

Extensions calling this get the resource definitions for these subsystem
registered in the host model, in addition to in the usual domain model
profile.
[WFCORE-452] Add OperationContext.isRegisterDeployers()

Throw exception if deployers are attempted added from a subsystem
installed on the HC.
[WFCORE-452] Support for configuring/persisting subsystems in host.xml.

MODEL part only
[WFCORE-452] Add first version of OC helper methods to determine if runtime step should run

Modify Abstract- Add-/Remove-/WriteAttribute Handlers to use the new
helper method.
[WFCORE-452] Rework ModelControllerServiceInitialization to boot op.

Previously the ModelControllerServiceInitialization loading was
hardcoded as part of the boot sequence. However, in order to use JMX as
a subsystem on the HC we need access to the services started by JMX's
MCSI. Putting these earlier also does not work, since patching's MCSI
needs to read values from the model, which do not get set until the boot
time. Hence this initialization has been refactored to an extra boot
RUNTIME step which has access to the model, and is able to install the
services JMX needs on a host.
[WFCORE-452] Get jmx working as a HC subsystem

Remove the hardcoded/duplicated HC RemotingConnectionService. We can now
configure it in host.xml.