feat(node-bindings): add methods for returning instance urls

[yash-atreya]

Motivation

The existing methods such as endpoint() and ws_endpoint() would return the URLs as a String. One would have to parse the String as a URL and then pass it to the provider.

Solution

Adds two methods endpoint_url() and ws_endpoint_url() which return the HTTP and WS urls respectively for both anvil and geth instances.

PR Checklist

• Added Tests
• Added Documentation
• Breaking changes

[yash-atreya]

cc @mattsse

[mattsse]

smol nit