Add custom-property-disallowed-list stylelint-polaris plugin

[aaronccasanova]

WHAT is this pull request doing?

This PR introduces a custom-property-disallowed-list plugin as a companion to the existing custom-property-allowed-list rule. The plugin will be added to the stylelint-polaris config in a follow up PR to disallow a collection of Polaris v10 custom properties prior to the v11 release.

const stylelintConfig = {
  rules: {
    'polaris/custom-property-disallowed-list': {
      disallowedProperties: ['--p-foo'],
      disallowedValues: {
        width: ['--p-foo', /--p-bar/ /* etc... */],
        '/.+/': ['--p-foo', /--p-bar/ /* etc... */],
      },
    },
  },
};

.class {
  --p-foo: red; // ❌
  width: var(--p-foo); // ❌
  color: var(--p-bar-baz); // ❌
}