Teach module.run state function to handle varargs

This is a fix for #4472, although I wound up implementing it a bit differently than I described in that issue.  I originally proposed we used a fixed argument called 'args' to specify the extra arguments.  This required additionally creating the special m_args to account for a function that had a "normal" argument called 'args'.  I decided this was not optimal.

The change I wound up doing detects the name of the vararg argument in the function definition and then allows you to just use that name.  For example:

```python
def func(*args):
    pass
```

you'd do the module.run state like this:

```yaml
test:
  module.run:
    - name: augeas.setvalue
    - args:
      - arg1
      - arg2
```

For this function:

```python
def func(*stuff):
    pass
```


You'd do:

```yaml
test:
  module.run:
    - name: augeas.setvalue
    - stuff:
      - arg1
      - arg2
```

This eliminates the need for the m_ special argument because there is no longer a corner case.  It also winds up being less code (11 lines vs 21).