Abstract particle bond handling

[RudolfWeeber]

Functions that deal with bonds (force/eneryg calculation, bond breakgge, collisin deteciotn, cluster analysis) should not know about how exactly the bond info is stored. See #4390 for background.

We allow for differnet storage formats for pair bonds and multi-partner bonds (#4390)

Steps

Implement storage-agnostic interface functions

in src/core/bonds.cpp/hpp (to be created). All of these are parallel calls. They will

• for now: create the respective BondView for the primary particle (first particle id in pair or multi-particle bonds) and insert/remove/find it in the Particle.bonds() of the primary particle (which is a BondList, i.e., a container for BondView)

• in the future: Create approprate bond views (which differ for all involved particles) and add/remove/find tehm on the p.bonds() for all involved particles

  • add_pair_bond(bond_id, p1_id, p2_id)
  • remove_pair_bond()
  • bond pair_bond_exists()
  • `add_multi_particle_bond(int bond_id, vector involved_particle_ids)
  • remove_...
  • ..._exists
  • for_each_bond(particle, pair_bond_kernel, multi_bond_kernel);. where the kernels take
    • for pair bonds: bond_id, p1_id, p2_id
    • for multi particle bonds bond_id, vector<int> involved_particle_ids