Add Monégasque (lij-mc)

In use in Wikidata for monolingual text [1] and lexemes [2].
For the autonym, see Dictionnaire Français-Monégasque [3] by the Comité National des Tradtions Monégasques and a page about the language [4] by the Académie des Langues Dialectales (Monaco).
Wikidata item: https://www.wikidata.org/wiki/Q56422

[1] 425d9d4779/lib/includes/WikibaseContentLanguages.php (L144)
[2] 548ead57fa/WikibaseLexeme.mediawiki-services.php (L27)
[3] http://www.traditions-monaco.com/dictionnaire-francais-monegasque
[4] http://www.ald-monaco.org/langues-monegasque/la-langue-monegasque-son-origine-et-sa-typologie-6

data/language-data.json

@@ -2382,6 +2382,13 @@
             ],
             "Ligure"
         ],
+        "lij-mc": [
+            "Latn",
+            [
+                "EU"
+            ],
+            "munegascu"
+        ],
         "liv": [
             "Latn",
             [