Additional Config Support

[sambrannon]

Hey there @MauricioRobayo 👋🏻

I ran into a situation where passing in additional gtag config options was helpful (specifically, adding server_container_url for Server-Side tagging). I wasn't seemingly able to do so out of the box with this package.

Any interest in a PR that would allow for this? I spiked out a barebones change that I think does the trick.

Notes

1. It exposes a new additionalConfig prop on the <GoogleAnalytics /> component that accepts all the same options as the @types/gtag.js package (which also allows for any custom tags, which confusingly server_container_url is 🤔)
2. The current approach feels more "one prop per config option", which is much simpler and nice, but this would allow for additional flexibility. Can see both sides. Any thoughts?
3. NextJS' 3rd-party script doesn't have any passable config options, maybe there's a different way to do all this?

In-Editor typeahead experience: