23 service improvements

[Kebslock]

This PR is mainly for complete review of the POI-, Track- and Vehicle-Service (because it was not done so far).

Furthermore there were changes to improve handling of GeoJSON data and also some minor code improvements.

[NiklasRentzCAU]

This looks good so far with the individual services and common utils on the side for all of them. Looking through the code comments: have you decided yet if you want to use / which logging framework you want to use? Answering this could solve a lot of the TODOs left in the code.
Good use of TODOs to keep track of minor things in the code to be replaced as the project progresses.
Also make sure to add a copyright/license header to your files, see my comment on the other PRs.

[NiklasRentzCAU]

stringifying and immediately parsing an object seems unnecessary/waseful. I guess you only want an object with the correct type for you to work on it or is there a reason why you would not want to work on the poi.position directly?

[Niatsuna]

Not an error but more like an inconsistency:
Sometimes you use the ?? (Nullish Coalescing) operator to either return the "right" value or if it is "null" another value, and then sometimes you use a if statement.

[n1kPLV]

This clearly needs a little bit more work. Please adjust call sites when changing the signature of functions:

> tsc && node ./build/index.js

src/routes/vehicle.route.ts(358,105): error TS2554: Expected 1 arguments, but got 2.
src/routes/vehicle.route.ts(371,100): error TS2554: Expected 1 arguments, but got 2.

[n1kPLV]

Also there is infinite recursion when calculating a vehicle position. getVehiclePosition() calls getVehicleTrackHeading(), which in turn calls getVehicleTrackDistanceKm(), which calls getVehiclePosition() again.

I am considering reverting this merge.