CmdPal: Possibility to edit Placeholder text for right-click overflow menu

### Description of the new feature / enhancement

It would be nice to be able to edit the placeholder text of the right-click overflow for a `CommandItem` :

Also, I think a better french translation would be `Rechercher une commande...` instead of `Commandes de recherche...`.

### Scenario when this would be used?

When an extension developer want to edit the placeholder text of the right-click overflow for a `CommandItem`.

### Supporting information

_No response_

Start by locating the CmdPal CommandItem implementation and the right-click overflow menu entry point. Check how the placeholder text and French localization are currently supplied; done means an extension developer can edit the placeholder and the French text reads "Rechercher une commande...".

Written by the indexing model from the issue text.