Test container type is added.

Test container is planned to test codezero microkernel extensively.
With these changes, everything is there to develop a full-featured test suite.
It also exemplifies how a new container type can be added to the system.
(cherry picked from commit f21fa53df421bfc8eeeaa096c89b98beed436c60)

conts/test/hello.c

@@ -0,0 +1,13 @@
+/*
+ * Autogenerated hello world print function
+ */
+
+#include <stdio.h>
+#include <container.h>
+
+int print_hello_world(void)
+{
+	printf("%s: Hello world from %s!\n", __CONTAINER__, __CONTAINER_NAME__);
+	return 0;
+}
+