Make HTML Language Service data driven

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• Pull data from https://html.spec.whatwg.org/multipage/indices.html#elements-3 (It even contains short descriptions!) into a JSON file
• Make HTML LS able to load such JSON files

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Additional data: https://developer.mozilla.org/en-US/docs/Web/HTML

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We get descriptions for all HTML attributes and 100 more html attributes:

[
  "html:version",
  "html:xmlns",
  "head:profile",
  "link:as",
  "link:importance",
  "link:importance",
  "link:integrity",
  "link:referrerpolicy",
  "link:title",
  "meta:scheme",
  "style:title",
  "body:alink",
  "body:background",
  "body:bgcolor",
  "body:bottommargin",
  "body:leftmargin",
  "body:link",
  "body:onblur",
  "body:onerror",
  "body:onfocus",
  "body:onload",
  "body:onredo",
  "body:onresize",
  "body:onundo",
  "body:rightmargin",
  "body:text",
  "body:topmargin",
  "body:vlink",
  "hr:align",
  "hr:color",
  "hr:noshade",
  "hr:size",
  "hr:width",
  "pre:cols",
  "pre:width",
  "pre:wrap",
  "ol:compact",
  "ul:compact",
  "li:type",
  "dd:nowrap",
  "main:undefined",
  "a:referrerpolicy",
  "bdo:dir",
  "br:clear",
  "ins:cite",
  "ins:datetime",
  "img:decoding",
  "img:decoding",
  "img:importance",
  "img:importance",
  "img:intrinsicsize",
  "img:referrerpolicy",
  "img:sizes",
  "iframe:allow",
  "iframe:allowpaymentrequest",
  "iframe:allowpaymentrequest",
  "iframe:csp",
  "iframe:importance",
  "iframe:referrerpolicy",
  "object:archive",
  "object:border",
  "object:classid",
  "object:codebase",
  "object:codetype",
  "object:declare",
  "object:standby",
  "object:tabindex",
  "param:type",
  "param:valuetype",
  "source:sizes",
  "source:srcset",
  "source:media",
  "area:accesskey",
  "table:align",
  "caption:align",
  "colgroup:align",
  "col:align",
  "tbody:align",
  "thead:align",
  "tfoot:align",
  "tr:align",
  "td:abbr",
  "td:align",
  "td:axis",
  "td:bgcolor",
  "th:align",
  "th:axis",
  "th:bgcolor",
  "form:accept",
  "form:autocapitalize",
  "button:autocomplete",
  "textarea:autocapitalize",
  "textarea:spellcheck",
  "meter:form",
  "dialog:open",
  "script:integrity",
  "script:nomodule",
  "script:referrerpolicy",
  "script:text",
  "canvas:moz-opaque"
]

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We need microsoft/vscode#67952 for shipping this feature.