fix: command issues

[clatapie]

This PR fixes the following main issues:

First issue

The first one was discovered in ansys/pymapdl#3385 (comment).
It was mainly involving empty argument handling as the following commands are not identical in MAPDL due to an additional coma in the first command:

*TREAD,PAR,FNAME,EXT,,NSKIP

*TREAD,PAR,FNAME,EXT,NSKIP

Second issue

Digging into the code, I also discovered some commands needed specific treatment. This is the case for SECMODIF for instance.

• PyMAPDL current documentation:
  

• MAPDL documentation:
  

• Incorrect MAPDL-CMD-CONV documentation:
  

The current proposition is the following:

    def secmodif(self, secid: str = "", kywrd: str = "", addional_command_arg: str = "", **kwargs):
        r"""Modifies a pretension section

        Mechanical APDL Command: `SECMODIF <https://ansyshelp.ansys.com/Views/Secured/corp/v232/en//ans_cmd/Hlp_C_SECMODIF.html>`_

        Parameters
        ----------
        secid : str
            Unique section number. This number must already be assigned to a section.

        kywrd : str
            The description of the argument is missing in the Python function. Please, refer to the product
            documentation for further information.

        addional_command_arg : str
            Additional arguments can be passed to the intial command. Please, refer to the product
            documentation for further information.

        Notes
        -----
        The :ref:`secmodif` command either modifies the normal for a specified pretension section, or
        changes the name of the specified pretension surface.
        """
        command = f"SECMODIF,{secid},{kywrd},{addional_command_arg}"
        return self.run(command, **kwargs)

An addional_command_arg has been added to the python argument that enable the user to pass whatever needed additional arguments (which vary depending on kywrd value).

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.95980% with 16 lines in your changes missing coverage. Please review.

Project coverage is 84.20%. Comparing base (d0ec620) to head (7590cc9).

Files with missing lines	Patch %	Lines
src/pyconverter/xml2py/ast_tree.py	93.26%	13 Missing ⚠️
src/pyconverter/xml2py/cli.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #374      +/-   ##
==========================================
- Coverage   84.37%   84.20%   -0.18%     
==========================================
  Files          13       13              
  Lines        2432     2500      +68     
==========================================
+ Hits         2052     2105      +53     
- Misses        380      395      +15     

Flag	Coverage Δ
coverage	84.20% <91.95%> (-0.18%)	⬇️

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[clatapie]

As discussed with @RobPasMue, a link has been added to redirect the user to the correct documentation webpage for additional or missing arguments.

I decided not to add the SECMODIF mention but the command documentation one to reducing repetitions in the docstring. This can be modified.