V5 add cli

This MR adds backports of the CLI from mHM v6 (see !91 (merged)):

• new command line interface to pass used pathes to mhm (mo_mhm_cli):

  Usage: mhm [options] <cwd>
  
  Options:
    <cwd>
        Description: The desired working directory (optional).
  
    --help / -h
        Description: Print this help message.
  
    --version / -v
        Description: Print the version of the program.
  
    --nml / -n <path>
        Description: The mHM configuration namelist.
        Default: mhm.nml
  
    --parameter / -p <path>
        Description: The mHM parameter namelist.
        Default: mhm_parameter.nml
  
    --mhm_output / -o <path>
        Description: The mHM output namelist.
        Default: mhm_outputs.nml
  
    --mrm_output / -r <path>
        Description: The mRM output namelist.
        Default: mrm_outputs.nml

• new module for interfaces to control mHM as a library (mo_mhm_interface):
  • mhm_interface_init: init routine to setup mHM with given namlist paths
  • mhm_interface_run: run mhm with current setup
  • mhm_interface_run_optimization: run parameter optimization with current setup
  • mhm_interface_finalize: finalize mhm (writing restart files of mhm and mrm)
• new module for messages during execution (mo_mhm_messages):
  • startup_message
  • domain_dir_check_message
  • finish_message
• new init and finalize routine for MPI in mo_common_MPI_tools:
  • mpi_tools_init
  • mpi_tools_finalize