DirectShow: Fix clang-tidy warnings about class definitions

- Use ' = default' for trivial constructors/destructors
- replace virtual by override or add override where applicable
- Replace trivial constructors by member initialization for simple structs
- Add Q_DISABLE_COPY where applicable
- Mark move assignment/move constructors as noexcept
- Remove unused member variables

Change-Id: I579fb69ebcd945b94de32b827d93e5a4dab4df97
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>