Feature request: pause at the end of the layer

[timur-tabi]

I would like to add a request that the "pause when UPS battery gets below X%" option include another option that the pause only occurs after the current layer is completed. If my UPS drops to 50%, I'm okay if it takes another 10% to finish the layer.

[kantlivelong]

I can see this being useful though it would need to be a best effort and try to complete the layer until below another threshold since layer time can vary greatly. We also have the issue where OctoPrint isn't aware nor exposes current layer info. Perhaps I could depend on DisplayLayerProgress or implement similar functionality.