As an Admin, I need to be able to customise the "Include Archived Content" string, if I decide to allow archived content among search results (See-PLANET-4595)

As we do with the "Load More" or other commands in Settings > planet4, we should include a command text box below the "Include archived content in search results" checkbox. This will allow people to customise the command.

To be clear, the expected behaviour of this command should be the same as "Load More" or "Donate button text" for multilingual sites, meaning this command should be customisable, depending on the language of the site (so, for multi-lingual sites, there should be 2 versions of the same commands)

See Snapshots or take Africa multilingual site as example https://release.k8s.p4.greenpeace.org/africa/wp-admin/options-general.php?page=planet4_options&lang=fr&admin_bar=1

If not customised, defualt text of the command should be "Include archived content"