refactor: unify exporters api

[ahmdmhd]

This PR is based on #144 and implements #148.

The following commands:

• compose
• jsonschema
• protobuf
• shacl
• vspec

now all accept the following flags:

• --expanded-instances
• --naming-config
• --root-type
• --schema
• --selection-query

--naming-config has been moved from the export group and was added to all individual export commands.

The aforementioned commands now benefit from a unified schema processing logic through process_schema and load_and_process_schema; the GraphQL schema is processed before being passed to the command handlers.

Schema instances are expanded by the processors. This creates intermediate types that reflect the expansion. For example, this schema:

type Cabin {
  seats: [Seat] @noDuplicates
}

type Seat {
  isOccupied: Boolean
  height: Int @range(min: 0, max: 100)
  instanceTag: SeatPosition
}

type SeatPosition @instanceTag {
  row: SeatRowEnum!
  position: SeatPositionEnum!
}

enum SeatRowEnum {
  ROW1
  ROW2
  ROW3
}

enum SeatPositionEnum {
  LEFT
  CENTER
  RIGHT
}

is expanded into:

type Cabin {
  Seat: Seat_Row!
}

type Seat {
  isOccupied: Boolean
  height: Int @range(min: 0, max: 100)
}

type SeatPosition {
  row: SeatRowEnum!
  position: SeatPositionEnum!
}

enum SeatRowEnum {
  ROW1
  ROW2
  ROW3
}

enum SeatPositionEnum {
  LEFT
  CENTER
  RIGHT
}

type Seat_Position {
  LEFT: Seat
  CENTER: Seat
  RIGHT: Seat
}

type Seat_Row {
  ROW1: Seat_Position!
  ROW2: Seat_Position!
  ROW3: Seat_Position!
}

The expansion process changes how the JSON Schema and .proto files are created. However, the end result is functionally identical.