Schwarz Contact: implement frictional contact

[ikalash]

Currently the code has frictionless contact, in which tangential forces are neglected. For frictional contact, the tangential forces will come from a friction law, e.g., Coulomb's law. Relevant parameters in the friction law will need to be read in and passed to appropriate locations within the code.

A simpler case than frictional (and frictionless) contact that is worse supporting is tied contact. Here, all components of the displacements would need to be transferred, rather than those only in the normal direction. The changes will need to occur here-ish in ics_bcs.jl.

[lxmota]

Also add tied contact, which should be the most simple version of contact.