IOC test framework - run from jenkins workspace not EPICS install dir

As a developer I would like the IOC test framework job to run the tests from the jenkins workspace it has checked out and not from the submodule of the epics distribution it has installed - currently a change to a test is not seen until a new EPICS clean build is generated by a separate jenkins job. It would also be nice if the device emulators could be updated and tested without also needing a new EPICS build, however we may with to keep them as part of EPICS for running devsim easily?

## acceptance criteria

* ioc test framework runs from local workspace and is removed from EPICS support
* ioc test framework can use its own copy of device emulators, checked out to a directory in this workspace
* decide if we wish to keep the device emulators submodule as part of EPICS support