[Mechanics] OpenMP Solver

[asmelko]

Summary
Create OpenMP mechanics solver.

Steps:

1. Create the same directory structure for kernel as in biofvm
2. Take sub-solvers one by one from paraPhysiCell and port them to this repository
3. Create an openmp_solver class, which will inherit solver that will initialize and call each subsolver (see biofvm solvers)
4. Write tests for each solver (use tests from paraPhysiCell)

Acceptance Criteria

• Solver builds and passes all tests