[ADD FEATURE] Adds a feed delay option to all sources.
This feature is an (optional) delay on the feeds you're getting (if you look under the app settings, there's a new dropdown that implements this). Some people might want articles that are at least 3 days old, or something like that. My colleagues, in particular, prefer to get their news a week late. This commit allows that possibility and only shows articles of a minimum age for all sources.
I might modify this in the future to allow individual delays per source, which I think would be more appropriate. As for now, I'd like to request feedback on what I should improve in this commit that would allow you to accept it.
Merged on my fork, It seems to work 👍
Would you be interested in porting this feature to the community fork? https://github.com/FluentFlame/fluent-flame-reader