[WIP] Allow upcasting

[captain-yoshi]

Unit tests with desired behavior from #943.

Any Tests Failures

/home/captain-yoshi/ws/ros/mimik_ws/src/BehaviorTree.CPP/tests/gtest_any.cpp:271: Failure
Expected: auto res = a.cast<std::shared_ptr<Greeter>>() doesn't throw an exception.
  Actual: it throws.
/home/captain-yoshi/ws/ros/mimik_ws/src/BehaviorTree.CPP/tests/gtest_any.cpp:273: Failure
Value of: a.castPtr<std::shared_ptr<Greeter>>()
  Actual: false
Expected: true

Blackboard Test Failure

C++ exception with description "The creation of the tree failed because the port [hello_greeter] was initially created with type [std::shared_ptr<HelloGreeter>] and, later type [std::shared_ptr<Greeter>] was used somewhere else." thrown in the test body.