handle @types and scoped @types

Author: aozgaa

src/services/codefixes/importFixes.ts

@@ -500,6 +500,15 @@ namespace ts.codefix {
                             }
 
                             relativeFileName = removeFileExtension(relativeFileName);
+
+                            if (startsWith(relativeFileName, "@types/")) {
+                                relativeFileName = relativeFileName.substr(/*"@types".length*/ 7);
+                                if (relativeFileName.indexOf("__") !== -1) {
+                                    // Double underscores are used in DefinitelyTyped to delimit scoped packages.
+                                    relativeFileName = "@" + relativeFileName.replace("__", "/");
+                                }
+                            }
+
                             if (endsWith(relativeFileName, "/index")) {
                                 relativeFileName = getDirectoryPath(relativeFileName);
                             }