Build and run the test program

This merge request adds the parallel/ddd/basic/test/ subdirectory to CMakeLists.txt and switches to dune_add_test to build the test program.

It also updates .gitlab-ci.yml to match the DUNE core modules. In particular it now builds the dune-common dependency instead of using the pre-build version from the duneci/dune:git image.

parallel/ddd/basic/test/CMakeLists.txt

-# -*- tab-width: 4; indent-tabs-mode: nil -*-
-set(TESTPROGS  testbtree)
-# programs just to build when "make check" is used
-set(check_PROGRAMS  ${TESTPROGS})
-# programs to run when "make check" is used
-set(TESTS  ${TESTPROGS})
-# define the programs
-add_executable(testbtree testbtree.cc)
-add_dune_ug_flags(testbtree )
-#include $(top_srcdir)/am/global-rules
-foreach(i ${TESTS})
-  add_test(${i} ${i})
-endforeach(i ${TESTS})
-# We do not want want to build the tests during make all
-# but just build them on demand
-add_directory_test_target(_test_target)
-add_dependencies(${_test_target} ${TESTS} ${COMPILE_XFAIL_TESTS})
\ No newline at end of file
+dune_add_test(SOURCES testbtree.cc)