[feat/command]: `reserve` command to reserve e3 for a period of time

[estarossa0]

The idea 💡

Make BMO handle E3 reservation for both campuses, by using reserve command.

Reasoning 🧠

Staff do announce on their events, but club members decide on theirs just between them, therefor clubs and students end up deciding to use E3 on same time, and fighting over who will be using it.

Solve it 🎯

you can just use reserve and give it date and BMO will tell you if it's reserved already by someone else or you can reserve it.

[Hessabra]

E3 reservation should be exclusive to khouribga since we don't have a space to reserve in the first place