Add a button to login with GitHub

[amoutonbrady]

Context

At the moment 100% of the shared playground are store in a Cloudflare KV store.
We would like to slowly transition away from that and store it on our own infrastructure based on Supabase.
The first part to do that is to implement authentication which would allow to save the REPL.

User Stories

• As an unauthenticated user, I load the playground page and click the "Sign In" button. I then proceed to authorize Github to communicate my information and I'm redirected to the playground. I see my username, indicating that the connexion is indeed made between the playground and my Solid account.

Functional rules

Given	When	Then
I'm on the playground	I click on the "Sign In" button at the top right corner	I'm redirected to a GitHub page that ask me if I allow Solid to use my information
I'm on the GitHub page that asks me about my information	I click on the "authorize button"	I'm redirected on the playground and I see my username on the top right corner in place of the Sign In button

Technical details

• We can largely inspire ourselves from the work that's been done over on the solid-hack repository: https://github.com/solidjs/solidhack/blob/main/src/pages/Submissions.tsx#L375-L380
• The API repository with the documentation that comes with it is located here: https://github.com/solidjs/solid-service-api
• The API is hosted here: https://api.solidjs.com