AMGX CONFIG FILE is not properly passed

[yslan]

Describe the bug
It appears that we don't pass the "AMGX CONFIG FILE" to solver->options so it's not using the user specified "amgx.json".

To Reproduce
In par file

[PRESSURE]
coarseSolver = amgx+device

[AMGX]
configFile = "amgx.json"

In the file src/solvers/elliptic/MG/coarseLevel.cpp, print the following

    std::string configFile;
    options.getArgs("AMGX CONFIG FILE", configFile); 
    std::string configFile2;
    platform->options.getArgs("AMGX CONFIG FILE", configFile2);

    if(platform->comm.mpiRank == 0) {
      std::cout << "\n ttt AMGX_CONFIG "<< configFile << "\n" << std::endl;  // This is empty
      std::cout << "\n ttt AMGX_CONFIG 2"<< configFile2 << "\n" << std::endl;  // This has the correct file
    }

Expected behavior
I think it will be nice to make AMG setup more verbose.
I propose to print AMGX solver config options in solvers/elliptic/amgSolver/amgx/AMGX.cpp
or calling something equivalent from AMGX to confirm the amgx.json is indeed used.

Desktop (please complete the following information):

• OS: Run and tested on Summit
• Version: v23

Credit to @yhmtsai who found this.