Resolves fdo#79276 Add fallback system for autocorrection of French variants

1) Replace the creation of acor_fr-FR.dat by acor_fr.dat since there's no specific for variants of fr
2) Add a fallback system to use it

Change-Id: Ia3e11fff0f266839dc148077b50c1b2f798d1c50
Reviewed-on: https://gerrit.libreoffice.org/9825
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>