[Progress Tracker] Support for Manual Trips and more stations

[MrKrisKrisu]

This pinned issue will document the progress of the project for Träwelling supporting manual trips and other stations
then known by "Deutsche Bahn HAFAS".
The goal is to change Träwelling this way, we are able to support multiple data sources.
To achieve this we want to use data from Wikidata and the IFOPT (Wikipedia, OpenStreetMap Wiki) as a unique identifier for stations.

Important

Dear API Consumers, in the next few weeks and months we will change some endpoints and the data structure of Träwelling.
Please be aware of this and check the changelog regularly as there will be breaking changes.
We try to keep the impact as low as possible and add backwards compatibility where it is possible.

Tip

If you enjoy maintaining data, Wikidata is a suitable platform to save structured data so that a large number of projects can benefit from it under a free license.
Many train stations, bus stops and more do not exist there or have not stored any associated IDs (IBNR, IFOPT/DHID, ...). Wikidata lives from people who volunteer data.
If you are interested in helping to improve the data quality of public transport stations, you can have a look at train stations in your area and add missing information.
Have a look at Karlsruhe Main Station (Q688541) as an example.

Manual trip creation

• Let closed beta users create trips manually with existing station data
  • Check if there are any error on frontend, backend and API side
  • Move trip creation from closed beta to experimental features (✨ move trip creation from closed to open beta #2427 )

Station support

• Add Columns for storing the Wikidata ID in the stations table (🗃️ first database layout for linking wikidata entities with stations #2389)
• Link local station entity with Wikidata entity and fetch raw data for testing (🗃️ first database layout for linking wikidata entities with stations #2389)
• Add Columns for storing the IFOPT ID in the stations table (every segment of the IFOPT ID should be stored in a
  separate column!) (🗃️ add database layout for IFOPT #2413)
• Fetch IFOPT from Wikidata if available
• Let users create stations from Wikidata Entities

Detach from using the IBNR as a unique identifier

• Change all API endpoints which are currently using the IBNR or the Name of a station as query to use the
  Träwelling ID
  • GET /trains/station/{name}/departures (♻️ migrate departures endpoint to use TRWL-ID #2410)
  • GET /trains/station/{name}/home (♻️ migrate home station endpoint to use TRWL-ID #2412)
• IBNR
  • Add station id to hafas_trips (🗃️ migrate trips table to use ID instead of IBNR #2443)
  • Remove station ibnr from hafas_trips (🗃️ drop origin and destination on hafas_trips #2580)
  • Make ibnr nullable (🗃️ make ibnr nullable #2579)
  • Update existing ibnr-less stations to null (there are some starting with 99999... in the database)