update dashboard layout / details

• Please replace the three-line logo with the two-line logo (explanation: Two- and three-line refers to the arrangement of "Metadata Collaboration" -> this is spread over one and two lines, so that together with the HELMHOLTZ placed above it, it becomes either two or three lines).
• Remove the FAIR Dashboard logo + GitLab logo from the bottom left of the footer
• Then use the HMC social icons on the left instead (Twitter aka X, Mastodon, Mattermost and now also LinkedIn (is not yet on the main page, but will be soon: https://www.linkedin.com/company/helmholtz-metadata-collaboration-hmc
• Also set this line via Imprint etc: HMC Dashboard on Open and FAIR Data in Helmholtz
• Please update the links to the imprint and privacy policy. At the moment you get a 500 Internal Server Error message, because the links are outdated
• add FAQ question "can I reuse the code of this dashboard?" to all subpages

These will be updated with next release - see MRs