add `outline` properties

[chharvey]

outline should be similar to border

{
      "name"     : "outline-color",
      "code"     : "oc",
      "summary"  : "Sets the color of an element’s outline.",
      "url"      : "https://developer.mozilla.org/en-US/docs/Web/CSS/outline-color",
      "inherited": false,
      "initial"  : "invert",
      "stability": 2,
      "values"   : [
      ],
      "generators": [
        {
          "name": "importValueType",
          "options": { "name": "<color>" }
        }
      ]
    },
    {
      "name"     : "outline-offset",
      "code"     : "oo",
      "summary"  : "Sets space between an element’s border and outline.",
      "url"      : "https://developer.mozilla.org/en-US/docs/Web/CSS/outline-offset",
      "inherited": false,
      "initial"  : "0",
      "stability": 2,
      "values"   : [
        { "name": "0", "code": "z" },
      ],
      "generators": [
        {
          "name": "generateSpaces",
          "transforms": { "namefn": ["length", "return `${length}rem`"] },
          "options": { "domain": "spacing", "negative": true }
        }
      ]
    },
    {
      "name"     : "outline-style",
      "code"     : "os",
      "summary"  : "Sets the line style of an element’s outline.",
      "url"      : "https://developer.mozilla.org/en-US/docs/Web/CSS/outline-style",
      "inherited": false,
      "initial"  : "none",
      "stability": 2,
      "values"   : [
      ],
      "generators": [
        {
          "name": "importValueType",
          "options": { "name": "<line-style>" }
        }
      ]
    },
    {
      "name"     : "outline-width",
      "code"     : "ow",
      "summary"  : "Sets the line width of an element’s outline.",
      "url"      : "https://developer.mozilla.org/en-US/docs/Web/CSS/outline-width",
      "inherited": false,
      "initial"  : "medium",
      "stability": 2,
      "values"   : [
        { "name": "0", "code": "z" }
      ],
      "generators": [
        {
          "name": "importValueType",
          "options": { "name": "<line-width>" }
        }
      ]
    },

[chharvey]

bangs v0.17.0 (UI)