Add 'select all' option to single select slicer

Currently in a single select slicer, there is no select all option.

I have come across several valid scenarios where the user should either select all values or a single value, but not the standard multi-select. Currently I use a workaround where I add a column to the dimension which contains the value 'All' for every row and I use this as the first level in a single-select hierarchy slicer, but this does increase the model size and would alternatively be possible with this simple option enabled.

I can see a similar feature is available in the new button slicer (preview) where you can simultaneously enable single select and show a 'select all' option, so it would be great to see this also implemented in the standard slicer including dropdowns.