Rework module linking (#4632)

The module linking process from jerry_parse is moved out into
a new jerry_module_link function, and jerry_parse is limited to
create unlinked modules.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/unit-core/CMakeLists.txt

@@ -58,6 +58,7 @@ set(SOURCE_UNIT_TEST_MAIN_MODULES
   test-lit-char-helpers.c
   test-literal-storage.c
   test-mem-stats.c
+  test-module.c
   test-native-callback-nested.c
   test-native-instanceof.c
   test-native-pointer.c