refactor: Proxy and cache avatar images (#907)

* refactor: proxy and cache user avatar images

* fix: extract keys

* fix: set avatar image URL

* fix: show the correct avatar in the list of available users in advanced request

* fix(s): set correct src URL for cached image

* fix: remove unexpired unused image when a user changes their avatar

* fix: requested changes

* refactor: use 'mime' package to detmerine file extension

* style: grammar

* refactor: checks if the default avatar is cached to avoid creating duplicates for different users

* fix: fix vulnerability

* fix: fix incomplete URL substring sanitization

* refactor: only cache avatar with http url protocol

* fix: remove log and correctly set the if statement for the cached image component

* fix: avatar images not showing on issues page

* style: formatting

---------

Co-authored-by: JoaquinOlivero <joaquin.olivero@hotmail.com>

server/index.ts

@@ -19,6 +19,7 @@ import { getSettings } from '@server/lib/settings';
 import logger from '@server/logger';
 import clearCookies from '@server/middleware/clearcookies';
 import routes from '@server/routes';
+import avatarproxy from '@server/routes/avatarproxy';
 import imageproxy from '@server/routes/imageproxy';
 import { getAppVersion } from '@server/utils/appVersion';
 import restartFlag from '@server/utils/restartFlag';
@@ -202,6 +203,7 @@ app
 
     // Do not set cookies so CDNs can cache them
     server.use('/imageproxy', clearCookies, imageproxy);
+    server.use('/avatarproxy', clearCookies, avatarproxy);
 
     server.get('*', (req, res) => handle(req, res));
     server.use(