Improve environment variable handling and reading (#5389)

* wip: better env var reading

* move most env vars to env.rs

* migrate more env vars

* more migration

* more migrations

* More migration

* 🦀 dotenvy is gone (almost)

* 🦀 dotenvy is gone 🦀

* Fix mural source account env var handling

* Remove defaults from admin key vars

* dummy commit to update github pr

* fix ci

apps/labrinth/src/auth/validate.rs

@@ -2,6 +2,7 @@ use super::AuthProvider;
 use crate::auth::AuthenticationError;
 use crate::database::models::{DBUser, user_item};
 use crate::database::redis::RedisPool;
+use crate::env::ENV;
 use crate::models::pats::Scopes;
 use crate::models::users::User;
 use crate::queue::session::AuthQueue;
@@ -146,7 +147,7 @@ where
                 user_item::DBUser::get_id(session.user_id, executor, redis)
                     .await?;
 
-            let rate_limit_ignore = dotenvy::var("RATE_LIMIT_IGNORE_KEY")?;
+            let rate_limit_ignore = &ENV.RATE_LIMIT_IGNORE_KEY;
             if req
                 .headers()
                 .get("x-ratelimit-key")