Feature: programmatically settable tasks for functions

[Silfalion]

So the objective of this issue is to suggest the introduction of a programmatically settable task scheduler for functions.

Right now function schedule is only set at the function creation and can only be changed in a way that overrides the previous schedule.

The suggestion would be to have a variable, as @Meldiron proposed(on Discord), for the execute method that would contain a datetime. The function would execute at that precise time.

This would allow to have for example 5 executions planed for a function with different inputs without changing the initial frequency of the function.

Another very interesting feature would also be, as Mattias Aabmets(Discord) suggested, to have yet another variable containing a cron for tasks for which the logic(function code) is known but frequency is erratic.

An example that would illustrate these 2 suggestions would be a reminder app. The first reminder that would take advantage of the first suggestion is setting up a datetime one day prior to a meeting to prep for it.

The second aspect of the example would be a reminder that rings me every few days(CRON) for my morning sport routine.

Right now I find myself needing to have a mini server that hit a function endpoint at a specific frequency/date that I set through the server's Api to emulate this feature , and I think it would be a powerful addition to appwrite if bundeled directly into it.

Looking forward to hearing your thoughts:)

[Silfalion]

I created the issue through the mobile app so it's not following the right template, creating another one and closing this one.