Add lcd_stop_all_gifs(void)

docs/lcd_api.md

@@ -229,6 +229,13 @@ Call this function before drawing over the GIF.
 This function should not be called on a GIF that has already been stopped (GIFs with a loop count will stop automatically).
 It is possible that the handler has been assigned to a new GIF, so it would stop the new GIF instead.
 
+#### Stopping all GIF animations
+```c
+void lcd_stop_all_gifs(void);
+```
+This function stops all the GIF animations and frees the memory allocated for the GIF.
+Call this function before drawing over the GIF.
+
 #### Checking if a GIF is still running
 ```c
 bool lcd_gif_is_playing(lcd_gif_t* gif);