Add a reminder command

[RealYusufIsmail]

Is your feature request related to a problem? Please describe.
Used to do remind people to do something in at a certain time or in a certain number of days, hour, etc

Can be useful to stop people from forgetting things.

Describe the solution you'd like
The user will be able to type /remindme time what to remind(optional)

[Zabuzard]

I feel like this would benefit from a more general solution, since #267 will also need such a feature. Possible synergy with #235 .

[DevSerendipity]

Can I be assigned to this?

[Tais993]

You've been assigned! Good luck

[DevSerendipity]

Thank you

[DevSerendipity]

I hope it won't be a problem, but I can start working on this command on Sunday so if anyone else wanna work on it, feel free to do it.

[Zabuzard]

I hope it won't be a problem, but I can start working on this command on Sunday so if anyone else wanna work on it, feel free to do it.

@IslamSakrak Are you still working on this? Otherwise, I might be willing to take this. (The persistence bit is a bit tricky to get right and #346 might be quite helpful as well)