Improve homepage
This MR brings the following improvements:
- Add copyrights at the top of the file
- Simplify HTML layout
- Change some gifs to be just a static screenshot but also add a dark and white variant of the screenshots.
- Add 3 small points linking to a few other KDE products (inter-linking)
- Remove metadata part, it's a very basic feature for a music player. Might be a good idea to add it again when Elisa supports writing metadata.
Screenshot:
Reviewers: