Footer redesign

[ainoc]

Implement new footer design: https://www.figma.com/file/N0Y3N0nfyMS2wG3gjwZ201/SD-Connect-Prototype?node-id=517%3A2533

Links (open in new tab):

Service description: https://research.csc.fi/-/sd-connect

[ainoc]

Text fixes:

SD Connect – Sensitiivisen datan palvelut / SD Connect - Services for Sensitive Data

CSC – Tieteen tietotekniikan keskus Oy / CSC - IT Center for Science Ltd.

[ainoc]

Add underline to link hover style.

[csc-felipe]

Texts need to be updated, and links are not opening in a new tab. In the future, it would be better to request changes before the PR is merged, or then to create a new issue with the new requests.