* [sdl2-gfx] Update to 1.0.4
* [sdl2-mixer] Update to 2.0.4 (#4934)
* [sdl2-image] Update to 2.0.4
* [sdl2-ttf] Update to 2.0.15
* [sdl2-gfx,-image,-ttf] Use vcpkg_extract_source_archive_ex()
- optional dependencies which are installed in vcpkg are automatically linked
- unavailable dependencies are marked as dynamically linked and dlls have to be copied manually if respective file formats are used