Segment restructure

[brad-richardson]

Description

Storing road data as JSON carries a number of issues and was always considered a "stop gap" during rapid feature iteration for transportation. As we approach GA, we need to properly schematize this data. It is proposed that this also includes some structure simplification ("flattening") for ease of querying, whereas before a priority was making the JSON nicely human-readable. I've left in road as-is to allow us to ship both deliveries for one release to ease migration.

Here is the high level schema change:

Old JSON path	New column
road.restrictions.speed_limits	speed_limits
road.restrictions.access	access_restrictions
road.restrictions.prohibited_transitions	prohibited_transitions
road.surface	road_surface
road.flags	road_flags
road.width	width_rules
road.lanes	lanes
road.level	level_rules

Additionally, for the non-geometry vehicle scoping block (when: vehicle:), we will simplify that frequently used structure as follows (note that this is a breaking change for consumers of this data):

speed_limits:
  when:
    ...
    vehicle:
      - dimension: <axle_count, height, length, weight, width>
        comparison: <greater_than, greater_than_equal, equal, less_than, less_than_equal>
        value: str
        unit: str

vs previously:

speed_limits:
  when:
    ...
    vehicle:
      axle_count:
        is_more_than:
          value:
          unit:
        is_less_than:
          ...
        ...
        ...
      height:
        ...
      length:
        ...
      weight:
        ...
      width:
        ...

See additional context in this discussion

Reference

1. RFC: Transportation structured columns #184
2. https://github.com/OvertureMaps/tf-transportation/issues/229

Testing

Updated all examples and counterexamples to reflect changes, including copying subproperties out of road to separate properties.

Checklist

1. Add relevant examples.
2. Add relevant counterexamples.
3. Update any counterexamples that became obsolete. For example, if a counterexample uses property A but is not intended to test property A's validity, and you made a schema change that invalidates property A in that counterexample, fix the counterexample to align it with your schema change.
4. Update in-schema documentation using plain English written in complete sentences, if an update is required.
5. Update Docusaurus documentation, if an update is required.
6. Review change with Overture technical writer to ensure any advanced documentation needs will be taken care of, unless the change is trivial and would not affect the documentation.

Documentation Website

Docs preview for this PR.

[BruceHarold]

Any problem using float to model speed limit vehicle dimension values?