OIDC: Support `picture` claim for use as user avatar

[Ghost-chu]

Describe the Bug

Although the OIDC response contains the picture field, the Bookstack still use default user avatar.

{
  "sub": "<censored>",
  "iss": "<censored>",
  "aud": "7acd8e81792f80dc48e9",
  "preferred_username": "<censored>",
  "name": "<censored>",
  "email": "<censored>",
  "picture": "https://cdn.<censored>/casdoor/avatar/<censored>/Ghost_chu.png?t=1685018195637388715"
}

Steps to Reproduce

1. Setup the OIDC for Bookstack
2. Create a new user and upload a avatar from your OIDC provider management
3. Login to Bookstack
4. Bookstack use default blue avatar as new user default avatar

Expected Behaviour

Bookstack should use the avatar from OIDC response instead the default avatar

Screenshots or Additional Context

No response

Browser Details

Brave 1.51.118 Chromium: 113.0.5672.126（Release） （64 bit）

Exact BookStack Version

v23.05.2

PHP Version

No response

Hosting Environment

debian-11.7 - Bookstack Docker Image by LinuxServer

      - AUTH_METHOD=oidc
      - AUTH_AUTO_INITIATE=true
      - OIDC_NAME=<censored>
      - OIDC_DISPLAY_NAME_CLAIMS=name
      - OIDC_CLIENT_ID=<censored>
      - OIDC_CLIENT_SECRET=<censored>
      - OIDC_ISSUER=<censored>
      - OIDC_ISSUER_DISCOVER=true

[ssddanbrown]

Thanks for raising, but I have recategorised this as a feature request, and updated the title to suit, since this is not a break in existing logic. We've just never specifically supported user avatars via the picture claim.

[cal940]

hello, is there any new progress on this issue?

would be nice to see this feature in the following releases.