Make image easier to use in non root mode + Cleanup (#958)

The main change is to make the config.yml link during the build.
The advantages are:

- No more annoying ln: /lichess-bot/config.yml: File exists message in log when a container is restarted.
- More importantly: for those, like me, who don't need custom extra_game_handlers.py or extra_game_handlers.py, this allows again (as in version 2024.5.1.2) to run a container based on this image as a non-root user without digging into the source code to guess what permissions are required to prevent the launch from failing with a permission error. Since the link is created during construction, no permissions are needed to use it at runtime. PS: Running a container as root on a production environment is a well-known worst practice. Copying extra_game_handlers.py or extra_game_handlers.py into the container file system still requires guessed permissions.

Easier in non root mode:
- Makes config.yml link in image, not at runtime.
Cleanup
- Removes useless ARG in Docker file.
- Removes useless files in image

docker/Dockerfile

@@ -12,8 +12,6 @@ COPY . .
 
 RUN python3 -m pip install --no-cache-dir -r requirements.txt
 
-ARG CONF_FOLDER=$LICHESS_DIR/config
-
-RUN chmod +x docker/copy_files.sh
+RUN chmod +x docker/copy_files.sh && ln -s $LICHESS_DIR/config/config.yml config.yml
 
 CMD docker/copy_files.sh && python3 lichess-bot.py ${OPTIONS} --disable_auto_logging

docker/Dockerfile.dockerignore

@@ -1,3 +1,5 @@
+docker/*
+!docker/copy_files.sh
 docs/
 wiki/
 .git*

docker/copy_files.sh

@@ -1,7 +1,5 @@
 #!/bin/sh
 
-ln -s /lichess-bot/config/config.yml /lichess-bot/
-
 if [ -e /lichess-bot/config/homemade.py ]; then
     ln -sf /lichess-bot/config/homemade.py /lichess-bot/
 fi