Allow Projects to have a featured Devlog

# Description:

Right now we show all the devlogs after sorting them by date. However we might want to have some devlogs as featured devlogs for the project that will always stay on top and then the rest can be scrollable list like the existing functionality

# Possible Fix

- Add a featured tag in Devlog Model
- Update `projects/[slug].astro` logic to show featured devlogs on top

