Day-night buffer asset

[samvanderzwan]

We need to add a day night buffer component, which is basically a simple storage with a small volume.
We need to discuss how complicated we want to make it, by also tracking the interface, and taking into account heat loss for example.
For control we can use the same as CHESS rule base,d which prioritizes the buffer over seasonal storage.
As use case the TUDelft wants to install a 800 m3 day night buffer.