Generic writer/reader for volume coupling

[MakisH]

In the context of #255, we discussed whether a generic reader/writer would make sense (@tirgendetwas). An additional use case (as discussed with Sergio Roget at the preCICE Workshop 2023) would be coupling forces over a porous medium. These forces should already be available in the objects registry, so a generic reader/writer should be able to access it.

To make it very generic, we could use a template for any (or even constrained) type.

Later on, we could also add a generic reader/writer for surface fields.

Potentially also related to #277 and related to #77, #150.