Port to hugo
Based on the previous MR from @carlschwan !4
On top of the initial MR it adds:
- Reworked Download page (similar to Kate)
- Added missing preview images for dark theme
- Added "Announcements" section to the main page
- Configured RSS section
- Change the post structure to keep images with the post (like Kate)
- Added link to "Extensions" store
- Fixed logo
- Fixed icons (at least in Falkon it looks normal, I am not sure of non-Falkon devices)
- Updated to hugo-kde go module
- Updated Gitlab-CI to run hugo