Add exports map to package.json of @typescript/twoslash

[benmccann]

I wanted to know if you'd be open to a PR for this. Twoslash distributes an ESM version, but there's no way to use it from Node.js since exports is not defined. We need to use the ESM version as some of our tooling is having issues with encountering a require

[jakebailey]

I would send a PR if you have one in mind, but I almost doubt that the ESM bundle is actually intended to be used from Node.