Use a valid finger ID when generating touch events from mouse events

Fixes https://github.com/libsdl-org/SDL/issues/9185

src/events/SDL_mouse.c

@@ -571,7 +571,7 @@ static int SDL_PrivateSendMouseMotion(Uint64 timestamp, SDL_Window *window, SDL_
             if (window) {
                 float normalized_x = x / (float)window->w;
                 float normalized_y = y / (float)window->h;
-                SDL_SendTouchMotion(timestamp, SDL_MOUSE_TOUCHID, 0, window, normalized_x, normalized_y, 1.0f);
+                SDL_SendTouchMotion(timestamp, SDL_MOUSE_TOUCHID, SDL_BUTTON_LEFT, window, normalized_x, normalized_y, 1.0f);
             }
         }
     }
@@ -754,7 +754,7 @@ static int SDL_PrivateSendMouseButton(Uint64 timestamp, SDL_Window *window, SDL_
             if (window) {
                 float normalized_x = mouse->x / (float)window->w;
                 float normalized_y = mouse->y / (float)window->h;
-                SDL_SendTouch(timestamp, SDL_MOUSE_TOUCHID, 0, window, track_mouse_down, normalized_x, normalized_y, 1.0f);
+                SDL_SendTouch(timestamp, SDL_MOUSE_TOUCHID, SDL_BUTTON_LEFT, window, track_mouse_down, normalized_x, normalized_y, 1.0f);
             }
         }
     }