SSDM-13521: Bringing back some core functionality

lib-base/source/java/ch/systemsx/cisd/base/unix/Unix.java

lib-base/sourceTest/java/ch/systemsx/cisd/base/AllTests.java

...ceTest/java/ch/systemsx/cisd/base/unix/UnixRootTests.java

...sourceTest/java/ch/systemsx/cisd/base/unix/UnixTests.java