feat: make ioredis configurable via environment variables (#3365)

* feat: expose ioredis client options

* run linter

* refactor redis client init into class extension

* explicitly handle constructor errors

* rename singletons

docker-compose.yml

@@ -4,6 +4,7 @@ services:
     image: redis
     ports:
       - "127.0.0.1:6479:6379"
+    user: "redis:redis"
   postgres:
     image: postgres
     ports:
@@ -12,6 +13,7 @@ services:
       POSTGRES_USER: user
       POSTGRES_PASSWORD: pass
       POSTGRES_DB: outline
+    user: "postgres:postgres"
   s3:
     image: lphoward/fake-s3
     ports: