Improve selection in the viewport (#720)

* improve selection in the viewport

* remove debug code

* updates following review feedback

- update API comments from /// to //! from
- add [[nodiscard]] attribute to member function
- move constructor implementations to .cpp files

* use lambda instead of ternary operator

* fix unit test failure caused by typo

Code/Framework/Tests/frameworktests_files.cmake

@@ -17,6 +17,8 @@ set(FILES
     BinToTextEncode.cpp
     ComponentAddRemove.cpp
     ComponentAdapterTests.cpp
+    ClickDetectorTests.cpp
+    CursorStateTests.cpp
     EntityContext.cpp
     EntityTestbed.h
     FileFunc.cpp