Counter of items [Features request]

[roliverosc]

Issue description

I would like to see a function added that will show us which is the selected rom number from the total number for each system. Example: '2/100' or '2 of 100'. I can't find this option or fuction in batocera.

[pajarorrojo]

Hi, Having that data in a new theme binding would be great. We already have the total number data, we just need the number of the selected rom/item.
In the theme we would use both variables and give it the desired format: 1-100 1/100 or 1 of 100 etc.