Handle CARPOOL in the legacy GraphQL API

[flaktack]

This should handle the CARPOOL mode in the GraphQL API, but I haven't tested yet since I don't have the GraphQL things set up locally.

Regenerating the generated files using the instructions in the README.md work using yarn, but produced significantly differing files compared to what is currently commited. Because of this I copied the relevant changes over manually.

65

[flaktack]

I've tested with a simple GraphQL query and it works as expected:

query{
  routes(transportModes: CARPOOL){
    id
    gtfsId
    agency { id }
    shortName
    longName
    mode
    type
  }
}

[leonardehrenfried]

Thanks a lot!