TypeScript definitions wrong for concerto-tools

[sstone1]

All of the code generation classes are exported under a top level CodeGen object:

https://github.com/accordproject/concerto/blob/master/packages/concerto-tools/index.js

The TypeScript definitions do not reflect this:

https://github.com/accordproject/concerto/blob/master/packages/concerto-tools/types/index.d.ts

So you can compile TypeScript that does this:

import { JSONSchemaVisitor } from '@accordproject/concerto-tools';

But it fails at runtime:

TypeError: concerto_tools_1.JSONSchemaVisitor is not a constructor