Add thermal boundary condition for particles

[lennertsprenger]

My unfinished work since my time at the HZDR is over

In the thermal boundary condition the particles that crossed the simulation boundary will be thermaly radiated from the point where the particle would have hit the boundary, with the velocity from the Maxwell Boltzmann distribution.

TODO:

• add temperature parameter
• check that the new position after the thermalization is not outside of the boundary of another axis
• extend docs

For now positive boundary offset is required (and checked for) due to #3850.

cc @steindev @sbastrakov

[sbastrakov]

@lennertsprenger you were right, it is actually required to check for all crossings in thermal implementation. In that regard, it is different from absorbing and reflecting, which were fully separable. I now fixed it, and also added some comments explaining the reasoning

[sbastrakov]

@psychocoderHPC this PR is now finished and ready for re-review.