Feature schema missing `name`, `order`

[martinhoyer]

tmt lint reporting false positives when order or name is added to feature prepare steps.

[LecrisUT]

Probably the schema files should be refactored a bit to use definitions and one_of. Maybe could try:

definitions:
  feature:
    properties:
      how:
        type: string
        enum:
          - feature
      epel:
        type: string
        enum:
          - enabled
          - disabled
one_of:
  - $ref: "/schemas/core#/definitions/core"
  - $ref: "#/definitions/feature"
required:
  - how

Dunno how well these mix though, particularly required over there. Having some reference would definitely be helpful for plugin development.