feat: rewrite with curl (VanityURL)

[Rushaway]

Description

Rewrite with curl (was in the todo list)

Motivation and Context

https://github.com/sbpp/sourcebans-pp/blob/php81/web/includes/SteamID/VanityURL.php#L20

How Has This Been Tested?

In run on my community since few weeks now with any errors/warnings

Screenshots (if appropriate):

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.