Adding a No-op task executor for testing

Fixing DFS implementation of DAG validation to be much faster
Adding in additional tests to ensure the run order of expanded tasks is preserved
Adding additional compile-time checks, resolving issues that came up as a result

CMakeLists.txt

@@ -3,6 +3,7 @@ project(overall)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED True)
 set(CMAKE_EXPORT_COMPILE_COMMANDS True)
+SET(CMAKE_CXX_FLAGS  "${CMAKE_CXX_FLAGS} -g -Wall -Werror")
 
 set(THIRD_PARTY_DIR ${CMAKE_BINARY_DIR}/third_party)