feat(auth): refactor auth, add oidc

Thanks to all HedgeDoc team members for the time discussing,
helping with weird Nest issues, providing feedback
and suggestions!

Co-authored-by: Philip Molares <philip.molares@udo.edu>
Signed-off-by: Philip Molares <philip.molares@udo.edu>
Signed-off-by: Erik Michelson <github@erik.michelson.eu>

frontend/src/components/common/user-avatar/hooks/use-avatar-url.ts

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2023 The HedgeDoc developers (see AUTHORS file)
+ * SPDX-FileCopyrightText: 2024 The HedgeDoc developers (see AUTHORS file)
  *
  * SPDX-License-Identifier: AGPL-3.0-only
  */
@@ -12,17 +12,17 @@ import * as identicon from '@dicebear/identicon'
  * When an empty or no photoUrl is given, a random avatar is generated from the displayName.
  *
  * @param photoUrl The photo url of the user to use. Maybe empty or not set.
- * @param displayName The display name of the user to use as input to the random avatar.
+ * @param username The username of the user to use as input to the random avatar.
  * @return The correct avatar url for the user.
  */
-export const useAvatarUrl = (photoUrl: string | undefined, displayName: string): string => {
+export const useAvatarUrl = (photoUrl: string | undefined, username: string): string => {
   return useMemo(() => {
     if (photoUrl && photoUrl.trim() !== '') {
       return photoUrl
     }
     const avatar = createAvatar(identicon, {
-      seed: displayName
+      seed: username
     })
     return avatar.toDataUri()
-  }, [photoUrl, displayName])
+  }, [photoUrl, username])
 }