add poisson solver to generate electrical field from non neutral charged gas densities

[Ehtyar]

Provide poisson solver
This is a continuation of PR #5366.

The poison solver is only solving the E-Field for the initial gas density not for densities created during the slide!

Use picongpu --help to see how to enable the poison solver

Poisson solver:
  --poisson.activate                    enable poisson solver
  --poisson.maxSteps arg (=2000)        maximum number of steps for the 
                                        preconditioner
  --poisson.epsilon arg (=1e-08)        maximal allowed error of the poisson 
                                        solver
  --poisson.preconditioner.disable      disable poisson solver preconditioner
  --poisson.preconditioner.maxSteps arg (=20)
                                        maximum number of steps for the 
                                        preconditioner

output during execution

...
PIConGPUVerbose PHYSICS(1) | Poisson solver:
PIConGPUVerbose PHYSICS(1) |   - converged after 74/100 iterations with norm=509.216, total epsilon=5.15989e-09
PIConGPUVerbose PHYSICS(1) |   - duration 3.5903 sec
...

Requires PR #5729

[psychocoderHPC]

Thanks for taking over!

Please reverence the original PR in the first comment this PR is replacing.
The original PR has a list of points we need to do, one nessesare is to extent the documentation for the command line paranater (rst file). It mostly mean copiing the docs from TBG_macros over to the rst file.

[psychocoderHPC]

As mentioned in #5366 we need to move forEachCell into PMacc first. One of the reasons is that we have two different licenses, one for PMacc and one for PIConGPU, if the code is going mainline we should have yhe correct license in.

[Ehtyar]

The original PR has a list of points we need to do, one nessesare is to extent the documentation for the command line paranater (rst file). It mostly mean copiing the docs from TBG_macros over to the rst file.

At least the TBG documentation rst file automatically includes the TBG_macros. Is there a separate rst file, that this should be referenced in?
The other points in the original PR I am still working on.

As mentioned in #5366 we need to move forEachCell into PMacc first. One of the reasons is that we have two different licenses, one for PMacc and one for PIConGPU, if the code is going mainline we should have yhe correct license in.

I can do that. Where in PMacc should it go? Do I need to do something more specific than moving the definition and make sure everything is properly included as neccessary?

[Ehtyar]

@psychocoderHPC @steindev Please have a look, when you are back.
I don't know, why it fails the ci tests but it should work otherwise.

After looking in the ci logs, apparently it works on some configurations but fails in others.

[Ehtyar]

Since I don't know a better way to run these tests, I will push a couple of times. Please excuse this.

[Ehtyar]

@chillenzer Please have a look at the pypicongpu and picmi changes.

[psychocoderHPC]

we need to wait for @chillenzer green 👍

[steindev]

Please explain the physical setup of the test as well.

[chillenzer]

Only reviewed the Python part for now. Looks plausible, some naming suggestions.