Add Haryanvi (Arabic script; bgc-arab) (#381)

Downstream task:
https://phabricator.wikimedia.org/T373561

data/langdb.yaml

@@ -97,6 +97,7 @@ languages:
   bft: [Arab, [AS], بلتی]
   bg: [Cyrl, [EU], български]
   bgc: [Deva, [AS], हरियाणवी]
+  bgc-arab: [Arab, [AS], ہریانوی]
   bgn: [Arab, [AS, ME], روچ کپتین بلوچی]
  # FIXME - currently says Bhojpuri, but it's a macrolanguage.
   bh: [bho]

data/language-data.json

@@ -585,6 +585,13 @@
             ],
             "हरियाणवी"
         ],
+        "bgc-arab": [
+            "Arab",
+            [
+                "AS"
+            ],
+            "ہریانوی"
+        ],
         "bgn": [
             "Arab",
             [