Breton and French name words: particle ar, generational suffix fils, and M. as a title #658

Three gaps from the CLDR corpus, each with its own collision question:

Katell ar Gall                  → middle 'ar', family 'Gall'        (Breton particle "the")
Jean-Nicolas de Bouchart fils   → family 'de Bouchart fils'         (French "Jr.")
M. Jean Dupont                  → given 'M.', middle 'Jean'         (French "Monsieur")

• ar as a particle: a US surname (231) and a Turkish one (8 Wikidata family bearers, trailing). As an ambiguous particle it would read like van does. Check it against Arabic transliterations (ar-Rahman), which are usually hyphenated.
• fils as a suffix word: collides. It's a US surname with 767 bearers and 5 Wikidata family bearers, and a suffix claim acts on exactly that last-word position. If added, it needs the ambiguous treatment ma/meng got (decisions.md#suffix-acronym-collisions), not plain suffix status.
• M. as a title: it has the same shape as Ó. in Liam Ó Murchú reads Ó as a middle initial: add the Irish particles Ó, Ní, Ua (and Malay binti) #604, a single letter with a period that is far more often an initial (Jean M. Dupont). It could only be claimed when leading and followed by a full name, which is a rule, not a word list. Possibly not worth it.