Extend SimpleFormIterator to enable/disable rendering of index

[pefi1011]

Is your feature request related to a problem? Please describe.
A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

The problem is UX-based - the index of an array is not always an useful/required/needed information

<ArrayInput >
          <SimpleFormIterator>
         ...
          </SimpleFormIterator>
   </ArrayInput>

Describe the solution you'd like

Conditional rendering of typography element

                            <Typography
                                variant="body1"
                                className={classes.index}
                            >
                                {index + 1}
                            </Typography>

It would be in the same fashion like disableRemove and disableAdd

<ArrayInput >
          <SimpleFormIterator disableIndex >
         ...
          </SimpleFormIterator>
   </ArrayInput>

Describe alternatives you've considered
As far as I understood, to disable rendering of Index I would need to implement my own SimpleFormIterator iterator

[pefi1011]

Here is the PR: #4908

Any feedback will be highly appreciated

[fzaninotto]

Fixed by #6305