Add script variants for Serbo-Croatian (sh-cyrl and sh-latn)

Script variants for Serbo-Croatian have been added to Names.php [1] as part of
the changes for adding a language converter [2].

[1] a573bea01b/includes/languages/data/Names.php (422)
[2] https://phabricator.wikimedia.org/T268033

data/langdb.yaml

@@ -634,6 +634,8 @@ languages:
   sg: [Latn, [AF], Sängö]
   sgs: [Latn, [EU], žemaitėška]
   sh: [Latn, [EU], srpskohrvatski]
+  sh-cyrl: [Cyrl, [EU], српскохрватски]
+  sh-latn: [sh]
   shi-latn: [Latn, [AF], Taclḥit]
   shi-tfng: [Tfng, [AF], ⵜⴰⵛⵍⵃⵉⵜ]
   shi: [shi-latn]