SSDM-13521: adding more methods to the Unix replacement library

lib-commonbase/sourceTest/java/ch/systemsx/cisd/common/io/PosixTest.java

+package ch.systemsx.cisd.common.io;
+
+import org.testng.annotations.Test;
+
+import java.io.File;
+import java.io.IOException;
+
+public class PosixTest
+{
+    @Test
+    public void testGetEuid()
+    {
+        int euid = Posix.getEuid();
+    }
+
+    @Test
+    public void testGetUid()
+    {
+        int uid = Posix.getUid();
+    }
+
+    @Test
+    public void testGetGid()
+    {
+        int gid = Posix.getGid();
+    }
+
+    @Test
+    public void testSetOwner() throws IOException
+    {
+        File file = File.createTempFile("pre", "su");
+        Posix.setOwner(file.getPath(), Posix.getUid(), Posix.getGid());
+        file.delete();
+    }
+}