[Feature] Allow users to specify custom Anisette URL

[Infinitay]

Request

This feature requests comes as a result of an issue I'm facing in #184. It turns out that the new Anisette endpoint ani.stikstore.app has Cloudflare protection while the old one ani.sidestore.io does not. It'd be nice if we could specify our own server to mitigate problems like this by using self-hosted servers or other servers which don't have any issues.

Contributor Checks

• I am willing to attempt to make a pull request with these requested features