Add ecommerce-store example

[tillrohrmann]

The ecommerce-store is copied over from
https://github.com/restatedev/example-shopping-cart-typescript.

This fixes #14.

[gvdongen]

LGTM 👍
For me, it runs locally and with the Docker compose setups. Did you try the AWS setup or should I quickly try that one as well?

[tillrohrmann]

LGTM 👍 For me, it runs locally and with the Docker compose setups. Did you try the AWS setup or should I quickly try that one as well?

I only tried it locally using Docker compose. If you could throw it on AWS, that would be helpful!