Add a shared credentials relationship from twitter.com to x.com

[rmondello]

Pour one out.

Overall Checklist

• [x] I agree to the project's Developer Certificate of Origin
• [x] The top-level JSON objects are sorted alphabetically
• [x] There are no open pull requests for the same update

for shared-credentials.json

• [x] There's evidence the domains are currently related (SSL certificates, DNS entries, valid links between sites, legal documents etc.)
• [x] If using from and to, the new group, the from domain(s) redirect to the to domain to log in.

[frogg]

🥺