Improvemnet: Add refresh command

[nonchris]

We should add some mechanism that allows a user to issue a manual refresh of one or more (?) certs.
This is useful to control if the renewal has worked.

This functionality should have some kind of limit per user.
@MayNiklas suggested to look if the time since last request is greater than x

The best way might be to wrap all requests in a data class which contains information of the issuer (chat id), the database entry (sql object) and the text that has to be sent, maybe even paired with it's own dispatch function which sends the data stored inside to it's issuer.

These objects could be held in a queue/ generator which yields the next entry when last request plus time x has passed.
This ensures that we don't exceed any API limits.

The daily refresh could use the same system too.