railway_manager_interface: update openapi

[JulesPeignier]

The railway manager's OpenAPI interface must be updated to take into account the new entries:

• The user must be able to link a posterior train and/or an anterior train.
• The user can select the train category.
• The user can specify whether there are any hazardous materials.
• The user can request to substitute a train, specifying the train name and departure date.

[Khoyo]

"update openapi" is not an acceptable commit message, see https://osrd.fr/en/docs/guides/contribute/contribute-code/commit-conventions/

[JulesPeignier]

Gesico train category, the user has to select: "A", "B", "C" or "Sans catégorie"

Should we rename it demand_category or circulation_category ?

[flomonster]

demand_category sounds okay for me.

If I remember right, in the corresponding feature ticket, we talked about renaming the variants of the enum to be more meaningful.

[flomonster]

LGMT (I just wonder about the enum variants of demand_category)

[Khoyo]

Ideally, that'd be railway_manager_interface: change openapi to allow substitute train, railway_manager_interface: change openapi to select anterior and posterior train, and railway_manager_interface: change openapi to add demand category and hazardous materials. But oh well

[JulesPeignier]

LGMT (I just wonder about the enum variants of demand_category)

I chose string because I think an enum would be too SNCF-specific