[FEAT] Move server_config.cfg into the data directory so it can easily be included in a docker volume.

[SeeJayEmm]

Is your feature request related to a problem? Please describe.
Currently the server_config.cfg sits in /planarally/ and any changes will be lost when the container is updated.

Describe the solution you'd like
server_config.cfg to a sub-directory so it can be mounted as a volume. Something like /planarally/config

Describe alternatives you've considered
An alternative would be a bind mount of the specific file. This would negate the benefits of using docker volumes.

Additional context
None

[Kruptein]

There actually is a specific config file for this reason under Dockerfiles/server_config_docker.cfg.
Which uses data/planar.sqlite as its default save location for similar reasons.

Though I will admit that it's slightly awkward to have two files and ideally this is just unified.