Implement Discord OAuth auth provider

Create the OAuth functionality, implement as a serviceprovider(?). In terms of who to allow access to, an admin role will be implemented. This will act similar to the Teamspeak's "server admin" role in which the user has full access to everything except giving the "server admin" role to anyone else (since that could be exploited).

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*Original: https://github.com/2bnb/website/projects/1#card-30534028*

The issue mentions implementing Discord OAuth as a service provider, with admin role controls similar to Teamspeak. First, examine existing authentication code and service provider structure in the codebase. Look for OAuth implementations or similar auth providers to understand the pattern. Determine how admin roles are defined and enforced elsewhere. The work involves integrating Discord's OAuth API, creating a new provider, and setting up role-based access controls.

Scritto dal modello di indicizzazione a partire dal testo della issue.