[Enhancement] Bound conformation tensor fields inside one of the fluids

Sometimes, the conformation tensor A might leak out of the liquid into gas which is not desirable.

A solution would be to advect A with the color function. A method similar to http://basilisk.fr/src/henry.h

Of course, that would require more work to make it compatible with three-phase (or multi-phase) formulations such as https://github.com/VatsalSy/hyphal-flow