Update configuration for Manchu (mnc) (#386)

This reflects the situation in core MediaWiki
and in real life.

Downstream task:
https://phabricator.wikimedia.org/T284043

Co-authored-by: SrishAkaTux <ssethi@wikimedia.org>

data/langdb.yaml

@@ -498,8 +498,9 @@ languages:
   mn: [Cyrl, [AS], монгол]
   mn-cyrl: [mn]
   mn-mong: [mvf]
-  mnc: [Mong, [AS], ᠮᠠᠨᠵᡠ ᡤᡳᠰᡠᠨ]
-  mnc-latn: [Latn, [AS], Manju gisun]
+  mnc: [Latn, [AS], manju gisun]
+  mnc-latn: [mnc]
+  mnc-mong: [Mong, [AS], ᠮᠠᠨᠵᡠ ᡤᡳᠰᡠᠨ]
   mni: [Mtei, [AS], ꯃꯤꯇꯩ ꯂꯣꯟ]
   mni-beng: [Beng, [AS], মেইতেই লোন্]
   mns: [Cyrl, [EU, AS], ма̄ньси]

data/language-data.json

@@ -3112,19 +3112,22 @@
             "mvf"
         ],
         "mnc": [
+            "Latn",
+            [
+                "AS"
+            ],
+            "manju gisun"
+        ],
+        "mnc-latn": [
+            "mnc"
+        ],
+        "mnc-mong": [
             "Mong",
             [
                 "AS"
             ],
             "ᠮᠠᠨᠵᡠ ᡤᡳᠰᡠᠨ"
         ],
-        "mnc-latn": [
-            "Latn",
-            [
-                "AS"
-            ],
-            "Manju gisun"
-        ],
         "mni": [
             "Mtei",
             [