Refactor CLI

[germa89]

The content of the CLI module should be able to be run as click-independent function.

So we should have:

@click.command(
    short_help="Stop MAPDL instances.",
    help="""This command stop MAPDL instances running on a given port or with a given process id (PID).

By default, it stops instances running on the port 50052.""",
)
@click.option(
    "--port",
    default=None,
    type=int,
    help="Port where the MAPDL instance is running.",
)
@click.option(
    "--pid",
    default=None,
    type=int,
    help="Process PID where the MAPDL instance is running.",
)
@click.option(
    "--all",
    is_flag=True,
    flag_value=True,
    type=bool,
    default=False,
    help="Kill all MAPDL instances",
)
def stop(port: int, pid: Optional[int], all: bool) -> None:
    """...."""
    from ansys.mapdl.core.cli.funcs import stop
    return stop(port=port, pid=pid, all=all)

This is in line with with the other project.

[germa89]

Partially done in #4329