slic3r: Fix missing includes in AVVideoDecoder

In file included from src/slic3r/GUI/AVVideoDecoder.cpp:1:
src/slic3r/GUI/AVVideoDecoder.hpp:28:20: error: ‘wxImage’ has not been declared
   28 |     bool toWxImage(wxImage &image, wxSize const &size);
      |                    ^~~~~~~
src/slic3r/GUI/AVVideoDecoder.hpp:28:36: error: ‘wxSize’ has not been declared
   28 |     bool toWxImage(wxImage &image, wxSize const &size);
      |                                    ^~~~~~
src/slic3r/GUI/AVVideoDecoder.hpp:38:10: error: ‘vector’ in namespace ‘std’ does not name a template type
   38 |     std::vector<uint8_t> bits_;
      |          ^~~~~~
src/slic3r/GUI/AVVideoDecoder.hpp:9:1: note: ‘std::vector’ is defined in header ‘<vector>’; did you forget to ‘#include <vector>’?
    8 |     #include <libswscale/swscale.h>
  +++ |+#include <vector>
    9 | }

src/slic3r/GUI/AVVideoDecoder.cpp:145:89: error: invalid use of incomplete type ‘class wxBitmap’
  145 |     bitmap = wxBitmap((char const *) bits_.data(), size.GetWidth(), size.GetHeight(), 32);
      |                                                                                         ^

src/slic3r/GUI/AVVideoDecoder.hpp

@@ -7,6 +7,11 @@ extern "C" {
     #include <libavcodec/avcodec.h>
     #include <libswscale/swscale.h>
 }
+#include <vector>
+#include <wx/bitmap.h>
+#include <wx/gdicmn.h>
+#include <wx/image.h>
+
 class wxBitmap;
 
 class AVVideoDecoder