Plugin architecture (#4861)

* wip

* Refactor, tasks, processors, routes loading

* Move Slack settings config to plugin

* Fix translations in plugins

* Move Slack auth to plugin

* test

* Move other slack-related files into plugin

* Forgot to save

* refactor

shared/utils/urlHelpers.ts

@@ -48,10 +48,6 @@ export function changelogUrl(): string {
   return "https://www.getoutline.com/changelog";
 }
 
-export function signin(service = "slack"): string {
-  return `/auth/${service}`;
-}
-
 export const SLUG_URL_REGEX = /^(?:[0-9a-zA-Z-_~]*-)?([a-zA-Z0-9]{10,15})$/;
 
 export const SHARE_URL_SLUG_REGEX = /^[0-9a-z-]+$/;