Pure vaapi capture (for capture target) and opengl composition for cursor only when capturing window and portal as well, clear background on resize for monitor capture

include/window_texture.h

@@ -7,6 +7,7 @@ typedef struct {
     Display *display;
     Window window;
     Pixmap pixmap;
+    EGLImage image;
     unsigned int texture_id;
     int redirected;
     gsr_egl *egl;