Modify `/plan-journey` so it returns bus polylines

[iswheeler]

Modify the backend /plan-journey endpoint so that it returns bus polylines in addition to walking polylines.

Remove any excess caching in the frontend client since it'll now have access to the direct bus path. (Make sure to check the cache isn't used by anything else important--e.g. the base map!)

[jumpy-cat]

• confirm format of patterns / bus routes in the backend, and data available during journey planning
• main implementation work
  • port patterns processing logic to backend
  • change /getAllRoutes, /getAllRideRoutes to return the processed data
  • change the api clients on the frontend to directly have deserialize the processed data, see if we can avoid writing fromJson manually and instead use json_serializable or generate from openapi definiton somehow
  • port journey bus polyline logic to the backend
    • add regression tests for detours being handled badly, because I made mistake also when porting...
  • update Journey types in the frontend and the response deserializing
  • update JourneyLayer to use the polyline, remove the map variant of routesCache
• deploy to mock backend

Extra Work Maybe

• test coverage of the new logic
• change patterns from current hash based cache system to something that reduces network xfer amounts?

Notes

• cachedGraph currently doesn't have the actual paths
• cachedRoutes and cachedRideRoutes have the bustime patterns data with no preprocessing, as suspected
• want to avoid duplicating the patterns processing logic; it should all be in backend if possible

Frontend Usage of Bus Patterns (main)

• /getAllRoutes -> BusAPi.fetchRoutes -> BusRepository.fetchRoutes -> BusProvider routes -> _MaizeBusCoreState -> _busProviderRef -------> _handleRoutesUpdated
• there are efforts done to not reparse and process routes (hash & fingerprint stuff), but fetch routes still happens every 5 seconds and does the preprocessing
• perhaps the frontend can, when requesting route line info, pass its existing version (simple number / string). The backend only sends the full data back if it has a newer version. (the backend can probably afford to do a deep equals check)

What does _handleRoutesUpdated do?

• populates _routePolylines and _routeStopMarkers
• calls _cacheRouteUpdates

What does _cacherouteUpdates do?

• populates _routePolylines and _routeStopMarkers... again ...
• And thats all

Frontend Usage of Bus Patterns (navigation-hub)

• BusProvider routes is used in
  • _showBusRoutesModal: its not actually used...
  • _updateAvailableRoutes: updates a rtid -> name mapping
  • _cacheRouteOverlays (2): _routePolylines, _routeStopMarkers, ...
  • baseRoutesLayer.cacheRoutes: sets the list cache
  • post frame callback -> _handleRoutesUpdated -> journeyLayer.setRoutesCache: sets the map cache

Usage of the list cache

• loads markers and polylines

Usage of the map cache

• just journey stuff, should be removed once possible