[idp] Add link to logo of demo.opencloud.eu

[tbsbdr]

Initial Checklist

• I understand this is a user story and questions should be posted in the Community Discussions
• I searched issues and couldn’t find anything (or linked relevant results below)

User Story

As a marketing manager I want that users can click on the login-logo so that they can get to the marketing website.

User Value

• encourages more exploration of marketing content
• increase visibility of marketing offers
• keep users within the brand ecosystem

Acceptance Criteria

• click on the logo opens https://opencloud.eu in new window

Visual

[AlexAndBear]

Wrong repo, this must go into opencloud as it's IDP related. We would need a new config option IdentifierDefaultBannerLogoTargetURI for that

[AlexAndBear]

Checked that with @dragonchaser as there is no lico config option for that, so there is not a quick win.

The clean solution is making an upstream PR to lico and add the new config option or delay this until we switch to authelia eventually

[dragonchaser]

WIP #684 and libregraph/lico#189