Add Typescript support

**Is your feature request related to a problem? Please describe.**
I've integrated `@googlemaps/extended-component-library` into a React application and noticed that Typescript is not yet supported.

I've also installed `@types/google.maps`, but it doesn't contain type annotations for these extended components.

**Describe the solution you'd like**
It would be great to include the types in this library or e.g., `@types/google.maps`.