Expanding the snap to functionality for monomers not connected via bonds and for monomer groups

[ljubica-milovic]

Background

This ticket represents an improvement of the previous one introducing the functionality #6215, as well as the POC #6153.

The first iteration covered only snaping of single monomers in relation to monomers with whom they have bonds with.
In this ticket, moving of multiple monomers and snaping to monomers who are not connected via bonds, are covered.

Requirements