separate unittest folder

unittests/cfdp/CMakeLists.txt

@@ -0,0 +1,12 @@
+target_sources(${FSFW_TEST_TGT} PRIVATE
+    testCfdp.cpp
+    testTlvsLvs.cpp
+    testAckPdu.cpp
+    testEofPdu.cpp
+    testNakPdu.cpp
+    testFinishedPdu.cpp
+    testPromptPdu.cpp
+    testKeepAlivePdu.cpp
+    testMetadataPdu.cpp
+    testFileData.cpp
+)