Add "Minimum time left" to Rolling Target sensor

[heisenberg2980]

Describe the feature

I would like to be able to specify the minimum time left in the rolling target sensors, so when there is less than that time left, the sensor will recalculate and jump to the next slot. For instance in a 3 hours rolling target sensor if this new parameter "minimum time left" is set to 2 hours, if the cheapest 3h window is from 1pm to 4pm the target sensor will show 1pm to 4pm until 2pm, and then at 2pm it will recalculate the next cheapest window for the day, which might be 8pm to 11pm

Expected behaviour

The new parameter "minimum time left" will force the target sensor to recalculate before the end of the period

Use Case

I use a target sensor to display on a screen the cheapest 3h window of the day, so everyone in the family knows when they should connect the non-critical appliances like the washing machine, dishwasher, etc. The problem is when there is for instance only 30min left, people keep asking what is the next window as 30min is not enough for any appliance to complete its cycle. It would be nice to be able to specify a "minimum time left" so the target sensor automatically jumps to the next window when there is no much time left

Confirmation

• By submitting this feature request, you agree that you have read the documentation and confirmed it does not already exist
• I am willing/able to help contribute to the solution of this feature

[BottlecapDave]

Hello. This feels like quite the edge case and not really what the sensors were built for. If support does go ahead, I'll need to think about how best to provide it as another niche config item in the setup.

It might be that I expose this functionality via the service instead where you can set the evaluation time. Or it might be something like #411 would be more suited.