Deployment Timer

[BONNe]

Description

Is your feature request related to a problem?

In #175 @wellnesscookie share his usage of "deployment" status. He uses it to give hype about upcoming challenges, which will be deployed at a certain time.
This feature could be automated.

Describe the solution you'd like us to implement.

Two new options for Challenge Object:
[] Deployment date -> Day/Time when challenge becomes available for completing.
[] Deployment timer -> How long challenge will be available for completion.

Additional context

This is an automation feature. It should not affect existing challenges, as well as default challenges should contain at least one example with this implementation.

[Espantonius]

It would also be nice to set challenges that can be completed from time to time.
Example: When a challenge is completed you have to wait 7 days to do it again. After 7 days if you complete it, then you have to wait another 7 days...

[BONNe]

Yes, this functionally does not go very well with "levels".
If the challenge is assigned to the level, player will not be able to progress untill he manage to get in time to complete a challenge.

[tastybento]

Interesting for seasonal/event challenges, but this needs design decisions before any implementation, so I'm parking it in the backlog rather than committing:

1. Should a timer actually flip the deployed flag, or just gate visibility? Auto-flipping means state changes with no admin action, which surprises people.
2. What happens to a level whose challenge expires? Players who arrive late can never complete that level — the interaction with levels is the real problem (Not show Challenges that are not deployed. #175/Uncountable in missing challenges #179 already showed how fiddly undeployed-challenge counting is).
3. Do we need history of past windows, or just current state?

If anyone watching has a concrete use case, describe it here — a daily/weekly rotation is a very different feature from a one-off launch date, and I'd rather build the narrow thing that's actually needed.