Consider Left-Hand mouse users for the Grab and Move feature

### Description of the new feature / enhancement

Both the Alt key and the Windows key are on the left side of the keyboard, but I have my mouse on the left side, so it means reaching over and holding down the key which is a little inconvenient. I would like to have the option to use the right Alt Gr key as the modifier for this feature.

### Scenario when this would be used?

Used every day by a user that has their mouse to the left of their keyboard.

### Supporting information

_No response_

Start by locating the Grab and Move feature implementation and its current Alt or Windows key modifier handling. Check how modifier options are configured and tested, then verify that the right Alt Gr key can be selected and activates Grab and Move for left-handed mouse users.

Written by the indexing model from the issue text.