Add ability to change the '/data' directory to another one, for example '/config'

[sunrize]

Is your feature request related to a problem? Please describe.
I had the same problem as in #14 and applied the same solution as in your comment, but it creates "ghost" directories inside appdata on the container host. Furthermore containers from LinuxServer.io and hotio.dev use /config path for application files and I would like to apply the same approach for Trailarr.

Describe the solution you'd like
Create an APP_DATA environment variable to specify the path for the Trailarr files. If it is not specified, then use the default path /data.

Describe alternatives you've considered
When path mapping is implemented, I assume that I will be able to mount the Sonarr and Radarr media folders under /media and redirect their paths there, that is, it will not interfere with /data.

Additional context
Right now my docker-compose.yml looks something like this:

services:
  ...
  sonarr:
    image: lscr.io/linuxserver/sonarr:latest
    container_name: sonarr
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Australia/Melbourne
    volumes:
      - /docker/appdata/sonarr:/config
      - /mnt/data:/data  # sonarr root folder /data/media/series
    ports:
      - 8989:8989
    restart: unless-stopped
  trailarr:
    image: nandyalu/trailarr:latest
    container_name: trailarr
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Australia/Melbourne
    ports:
      - 7889:7889
    volumes:
      - /docker/appdata/trailarr:/data
      - /mnt/data/media:/data/media  # this creates 'ghost' subdirectories under /docker/appdata/trailarr on the host
    restart: on-failure
  ...

With APP_DATA environment variable, it will look like this:

services:
  ...
  trailarr:
    image: nandyalu/trailarr:latest
    container_name: trailarr
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=Australia/Melbourne
      - APP_DATA=/config
    ports:
      - 7889:7889
    volumes:
      - /docker/appdata/trailarr:/config 
      - /mnt/data/media:/data/media
    restart: on-failure
  ...

[nandyalu]

This can be added!