[WIP] Enable conditional validation of fields in DDF forms

[skateman]

This is the implementation of the idea proposed here, basically allowing to use the same condition syntax that is already available when displaying/hiding fields. It is wrapping each validator in the validatorMapper with the condition parsing that has been exposed for external usage.

[
  {
    component: componentTypes.SELECT,
    name: "country",
    label: "Country",
    options: [
      { value: "us", label: "United States" },
      { value: "xx", label: "Other" },
    ],
  },
  {
    component: componentTypes.TEXT_FIELD,
    name: "state",
    label: "State/province",
    validate: [
      {
        type: validatorTypes.REQUIRED,
        condition: {
          when: "country",
          is: "us"
        }
      }
    ],
  }
]

This would (partially) solve an issue in the IBM Cloud provider form where some fields would be not required if a dropdown is set to the right value. However, it doesn't deal with the visibility of * and some other aspects, so I am also considering to create a specialized wrapper component (with a fields attribute similarly to the validator) that would solve all the issues by altering the schema of the fields beneath.

Even if I go with the other solution, this might be useful in other areas and so I'm leaving it here for discussion as a draft.

[miq-bot]

Checked commit skateman@736a8be with ruby 2.6.3, rubocop 0.69.0, haml-lint 0.28.0, and yamllint
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Everything looks fine. 👍

[miq-bot]

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