Json Schema update

[isabelle-dr]

This is an issue to track the JSON Schema update that is planned in Q4 2021.

The main goals of this update are:
1- Assess differences between the schema from this repo and the schema from the gbfs-validator repo and keep only one "source of truth" Json Schemas for all versions
2- Review open issues and PR's on both this repo and the gbfs-validator repo and modify the "source of truth" Json Schema accordingly
3- Reorganize the GBFS versions in different folders instead of using the tags

[isabelle-dr]

The Json Schemas on the validator repository contain some additional fixes that have been done while building the tool.
They will be taken as the base for the "source of truth".
While comparing the two different sources, I noticed that:

• the descriptions are missing from the v1.0 files
• the fix that has been done in gbfs-json-schema/pull/44 needs to be done for v2.1

Order of execution:

• Create a PR with the JSON schema taken from the validator
• Update the v1.0 files with the descriptions
• fix v2.1 geofencing zones (ref)
• Address the following PR's / issues
  • Remove version field in v1.0 schema #53 [fixed]
  • Fix max_range_meters conditionally required on vehicle_types.json #45 [fixed]
  • Required fields in system_pricing_plans plan object was incorrectly placed #49 [fixed]
  • Fix vehicles_types_available to vehicle_types_available #50 [fixed]
  • Update geofencing_zones.json #52 [fixed]
  • Remove vehicles from station status #55 [fixed]
  • Error in schema of system_calendar gbfs-validator#45 [fixed]
  • Use integer type for integer fields #51 [fixed]
  • Why there is not a description of the data in system_regions schema? #48 [fixed]
• Add a schema for the 2.3RC