Add stops.bikes_boarding

### Describe the problem

An indication of the capacity to transport bicycles can only be found in Trips.bikes_allowed.

The GTFS therefore considers the issue of the carriage of bicycles in its current version only from the point of view of the public transport vehicle.

For wheelchairs, the authorisation to carry is conditional on Stops.wheelchair_boarding and Trips.wheelchair_accessible.
There is a relationship between the infrastructure and the transport vehicle.

It turns out that the physical location of a stopping point, its road geometry characteristics may or may not allow the carriage of bicycles, for safety reasons in particular.

This is especially true when the transit vehicle uses bike racks on the back. These devices require the Customer to be in the back of the vehicle and potentially on the road.

For bicycles, it is therefore necessary to make the relationship between the infrastructure and the transport vehicle.

### Use cases

A physical stop somewhere

if off-road
bikes boarding is possible without risk of accident

if on-road
bikes boarding is impossible due to the risk of an accident

if The bus stop is on the public road it could not allow for the maneuvering of the bike rack.

etc.

### Proposed solution

Addition of `bikes_boarding`, Enum, Conditionally Forbidden:

Indicates whether bike boardings are possible from the location. Valid options are :

0 or empty - No boarding information for the stop.
1 - Some bike at this stop can be boarded by a rider.
2 - Bike boarding is not possible at this stop.

Conditionally Fordiden :

For locations which are stations (location_type=1), entrances (location_type=2), generic nodes (location_type=3) or boarding areas (location_type=4).
Forbiden

### Additional information

_No response_