Add new features, fix .env setup, fix permissions and UID conflicts

[Pavlogal]

I've addressed all complaints from #49 and some more.

Changes:

• Re-added support for Jackett, thus addressing: Added support for Jackett #10 (comment)
• Added FlareSolverr, thus solving FlareSolverr support #48 (comment)
• Fixed audiobookshelf, thus solving Docker-compose missing multiple containers #44 (comment)
• Added automatic timezone detection feature to main.py (it just reads from /etc/timezone),
• The python script can now act as a compose file generator, as it asks the user if they actually want to set up folders and permissions.
• Resolved UID conflicts, while keeping the others the same as before
• Fixed manual setup by making new .env and docker-compose.yml samples. This also gives the end user the ability to customize container UIDs for manual installs. I also changed the provided compose file to a .sample, so it's more like the .env sample and the user will always have a copy of the original even if overwritten by the python script.
• Since we're endorsing compose v2 I removed version from docker-compose.yml so compose v2 doesn't complain about it. Also added a note to README.
• Added a script to remove old users and an update script
• Updated README to reflect changes and added a note for NFS users to save them some trouble

I tried to keep my commit history as clean as possible so I hope reviewing this will be easy, although I did make quite a lot of changes. I did some testing and everything should work perfectly now.

[Pavlogal]

It failed the docker-compose check because there is no longer a docker-compose file but just a sample. It wouldn't work anyway now since docker-compose.yml now depends on .env for manual installs. Checks should be rewritten or I can simply add a python-generated compose file which is hardcoded and should work in the current workflow.

[Ulimn]

It failed the docker-compose check because there is no longer a docker-compose file but just a sample. It wouldn't work anyway now since docker-compose.yml now depends on .env for manual installs. Checks should be rewritten or I can simply add a python-generated compose file which is hardcoded and should work in the current workflow.

You could add something like a "sample" ci-compose.yml and use it in the CI with the -f flag.