Bundle maps into build artifacts

[StenAL]

Description

With this change, the server no longer needs to be deployed alongside a tracks directory and the symlink to the tracks directory can also be removed, making the server work without any changes on Windows.

Tracks are now bundled into the jar file generated by mvn package, however the location where tracks are searched for can still be overridden with a CLI flag.

This required changing the way FileSystemStatsManager and FileSystemTrackManager load tracks by making it possible to configure which kind of file system they should use as jar resources can only be read as files when using a bespoke FileSystem.

Also a bunch of duplicate unused assets have been removed. See individual commits for more details.

Testing

• ran Maven's exec:java task from IntelliJ, which successfully loaded maps from the resources path
• ran jar using CLI (java -jar server/target/server-2.1.2.0-BETA.jar), which successfully loaded bundled maps
• ran jar using CLI with --tracks-dir argument (java -jar server/target/server-2.1.2.0-BETA.jar --tracks-dir server/src/main/resources/tracks), which successfully loaded maps from my filesystem

[PhilippvK]

@pehala FIY

[StenAL]

Changes since last review:

• clarified how to use custom tracks in README
• fixed CI
  • removed the assembly-tracks build step in the shared project which created a zip file of all tracks. This is not needed anymore because tracks are now bundled into the jar file.
  • removed the Upload Tracks step from CI

[PhilippvK]

Look fine for me. If I receive no complaints until Monday this gets merged!