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/test/api_v2/mod.rs

@@ -3,6 +3,7 @@ use super::{
     environment::LocalService,
 };
 use crate::LabrinthConfig;
+use crate::env::ENV;
 use actix_web::{App, dev::ServiceResponse, test};
 use async_trait::async_trait;
 use std::rc::Rc;
@@ -46,10 +47,7 @@ impl Api for ApiV2 {
     async fn reset_search_index(&self) -> ServiceResponse {
         let req = actix_web::test::TestRequest::post()
             .uri("/v2/admin/_force_reindex")
-            .append_header((
-                "Modrinth-Admin",
-                dotenvy::var("LABRINTH_ADMIN_KEY").unwrap(),
-            ))
+            .append_header(("Modrinth-Admin", ENV.LABRINTH_ADMIN_KEY.clone()))
             .to_request();
         self.call(req).await
     }