follow up on #6614

Related issues: #247 (comment), #5787, #2709, #6371 (comment)

Problems:

• Can not easily specify a loader extension for json or css (e.g. `json!a.json); currently every resources needs to have its own declaration
• Problem with migrating to .ts, with modules that do not have typings, and users just want to get by

Proposal:

• Allow for short hand module declarations:

  declare module "foo";

  to be equivalent to:

  declare module "foo" {
      var _temp: any;
      export = _temp;
  }

• Allow module names to have a wildcard character and match that in lookup

  declare module "json!*" {
      let json: any;
      export default json;
  }
  import d from "json!a/b/bar.json";
  // lookup:
  //    json!a/b/bar.json
  //    json!*

• Additional the module "*" would allow for matching all unknown modules in the system, which can be used as a way to suppress all missing module errors

  declare module "*";
  import d from "some\unknown\module"; // no error, d is any

• Report no-implicit-any errors for modules declared using the shorthand notion
  Open issue: is this reported on declaration or use sites