Rename "api_key" form element to be compatible with "Services API Key Authentication"

Alright done! Also did a few unrelated changes. Originally, I didn't want to provide an update hook, since this is still an alpha build, but for the api key this is actually important. I also added the other configs, since now an update hook exists anyway.

Please review!

Mhm this isn't really something we need to fix in posthog, because we already have the posthog context. What happens in the related issue simply shouldn't happen.

I don't really like to add workaround for things like this, tomorrow it might be another word that's broken. Not our job to fix this here.
Let's instead resolve 🐛 namespace "api_key: causes access denied if a form has element also called 'api_key' Fixed asap! :)