Using VS Code Go to Declaration support

VS Code 1.30 adds support `go to declaration`. This supplements the existing `go to` commands we already have for TypeScript: * `go to definition` * `go to type definition` * `go to implementation` Although this was added mainly to support languages like C++, I wonder if typescript tooling could also use `go to declaration`. Some ideas: * https://github.com/Microsoft/TypeScript/issues/14588 * Going to the `d.ts` file (even if declaration map file exists)