Make OTG window resizable

PR #3219 <https://github.com/Genymobile/scrcpy/pull/3219>

app/src/usb/screen_otg.c

@@ -72,7 +72,8 @@ sc_screen_otg_init(struct sc_screen_otg *screen,
     int width = params->window_width ? params->window_width : 256;
     int height = params->window_height ? params->window_height : 256;
 
-    uint32_t window_flags = SDL_WINDOW_ALLOW_HIGHDPI;
+    uint32_t window_flags = SDL_WINDOW_ALLOW_HIGHDPI
+                          | SDL_WINDOW_RESIZABLE;
     if (params->always_on_top) {
         window_flags |= SDL_WINDOW_ALWAYS_ON_TOP;
     }