Add Høgnorsk (nn-hognorsk)

In use in Wikidata for lexemes [1].

For the autonym, see e.g. the Nynorsk Wikipedia's Høgnorsk version of the page
about Høgnorsk [1]. I've followed the same format as Bokmål and Nynorsk for
consistency.

[1] https://github.com/wikimedia/mediawiki-extensions-WikibaseLexeme/blob/548ead57fa89125962425efd6268d5c040353532/WikibaseLexeme.mediawiki-services.php#L27
[2] https://nn.wikipedia.org/wiki/Hn/H%C3%B8gnorsk

data/langdb.yaml

@@ -453,6 +453,7 @@ languages:
   nl: [Latn, [EU, AM], Nederlands]
   nmz: [Latn, [AF], nawdm]
   nn: [Latn, [EU], norsk (nynorsk)]
+  nn-hognorsk: [Latn, [EU], norsk (høgnorsk)]
  # There's also nb for Bokmål and nn for Nynorsk
   "no": [Latn, [EU], norsk]
   nod: [Lana, [AS], ᨣᩴᩤᨾᩮᩥᩬᨦ]

data/language-data.json

@@ -2954,6 +2954,13 @@
             ],
             "norsk (nynorsk)"
         ],
+        "nn-hognorsk": [
+            "Latn",
+            [
+                "EU"
+            ],
+            "norsk (høgnorsk)"
+        ],
         "no": [
             "Latn",
             [