Implement tagged templates (blocked on TypeScript#49552)

[flightofthefox]

Note to check in on microsoft/TypeScript#49552 periodically.

This would allow using a tagged templates to interpolate while still returning strong types:

const result = await DB.query(sql`SELECT * from posts WHERE author = ${userId}`);
if (result[0]) {
  console.log(result[0].id); // Has type completion/checking for fields
}