Add OpenID SSO icon

When admins configured an OpenID connect identity provider
(https://docs.gitlab.com/ee/integration/openid_connect_provider.html),
no icon would be displayed by default. We now include a 64x64 OpenID
icon from https://openid.net/add-openid/logos/.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/214390

app/helpers/auth_helper.rb

 # frozen_string_literal: true
 
 module AuthHelper
-  PROVIDERS_WITH_ICONS = %w(twitter github gitlab bitbucket google_oauth2 facebook azure_oauth2 authentiq salesforce atlassian_oauth2).freeze
+  PROVIDERS_WITH_ICONS = %w(twitter github gitlab bitbucket google_oauth2 facebook azure_oauth2 authentiq salesforce atlassian_oauth2 openid_connect).freeze
   LDAP_PROVIDER = /\Aldap/.freeze
 
   def ldap_enabled?

changelogs/unreleased/sh-add-openid-sso-icon.yml

+---
+title: Add OpenID SSO icon
+merge_request: 54026
+author:
+type: changed

spec/helpers/auth_helper_spec.rb

@@ -73,12 +73,12 @@ RSpec.describe AuthHelper do
 
   describe 'enabled_button_based_providers' do
     before do
-      allow(helper).to receive(:auth_providers) { [:twitter, :github, :google_oauth2] }
+      allow(helper).to receive(:auth_providers) { [:twitter, :github, :google_oauth2, :openid_connect] }
     end
 
     context 'all providers are enabled to sign in' do
       it 'returns all the enabled providers from settings' do
-        expect(helper.enabled_button_based_providers).to include('twitter', 'github', 'google_oauth2')
+        expect(helper.enabled_button_based_providers).to include('twitter', 'github', 'google_oauth2', 'openid_connect')
       end
 
       it 'puts google and github in the beginning' do