Technical: Refactore the API to use only the nginx cache or only a cache in filesystem

[Tsukoyachi]

Idea of @Apoorva64 :
Use the nginx cache to have better handling of TTL and to make the api stateless

My idea :
All the satellite API will return 2 TLE lines that are the only mandatory data so in memory once the data is loaded, we can make a go routine to save these data in a json file with this format :

This solution also allow us to be more efficient with the revail date of the cache. And it's also easier to implement than adding an other layer for this.