Improve sort order in assertions

How it is works now

if you want a sort property that contains an array of primitives, the config would look like this:

assert/sort-something:
    subject:
      type: Schema
      property: enum
    assertions:
      sortOrder:
        direction: 'asc'

If the property contains an array of objects, you must specify the property you want to sort by

Example:

 assert/sort-something:
    subject:
      type: PathItem
      property: parameters
    assertions:
      sortOrder:
        direction: 'asc'
        property: name  # The name of the property by which the sorting occurs

If you do not specify subject property, sortOrder will use an array of object keys

Example:

   assert/sort-something:
    subject:
      type: PathItem
    assertions:
      sortOrder:
        direction: 'asc'

Will check sort order of keys from PathItemObject: [ 'summary', 'parameters', 'get' ]

Problem

If you have an array of objects and don't specify a subject: property sortOrder will check order of the keys in each object

Solution

Check if subject: type is an array type and subject: property not specified then check the sort order by value (instead key) and if assertion: property not specified display the warning message

Start by locating the sortOrder assertion implementation and its tests; the issue provides YAML examples for primitive arrays, object arrays, and omitted subject properties. Trace how subject type and property are interpreted, then add coverage for sorting array values and for the warning when assertion property is absent.