editoast: add level crossings to railjson_generator and infra export import

[Wadjetz]

fix #14252 fix #14222

This Pr add level crossing to railjson_generator and import/export of infra

• Add level crossing python types to railjson_generator
• Add level crossing builder function to railjson_generator
• Add some examples of level crossing to small_infra
• Add level crossing types to editoast import and export of infra
• Bump railjson version to 4.5.0

[github-actions]

⚠️ API changes

This Pull Request introduces some changes in the API:

• please own it: notify or even prepare dedicated PR(s) to consumer projects

Changes in Schemas

Dear @Wadjetz, please ensure the following:

• changes should match in osrd_schemas and editoast schemas
• the RailJSON version in osrd_schemas::infra.py and editoast schemas::infra::railjson.rs should match and be bumped on any change of infra schemas (same goes for rolling-stock between osrd_schemas::rolling_stock.py and editoast schemas::rolling_stock.rs)
• the version of the Python package in osrd_schemas::pyproject.toml should be bumped on any change

[flomonster]

LGTM, and tested.

I could not visualize the level crossing within osrd map viewer. After debuging it's because the generated sprite did not contained the level crossing sprite within the downloaded editoast docker image. Which is weird... Since this is not related to this PR I approve and we can merge it.

[eckter]

LGTM for the (very small) core changes.

Note: level crossings are supposed to be used in the simulation, especially for ETCS. I get that it's not currently in scope, but it would be nice to keep track of that somewhere.

[aschantraine]

LGTM, just small things.

[flomonster]

We need the DCO and then we're good to merge 🎉