i18n: rename .po files

This seems to be the defacto standard for naming `.po` files. See the
GTK source code [1] as an example. I was unable to find any definitive
documentation on the naming.

Replaces: #10905

[1] https://gitlab.gnome.org/GNOME/gtk/-/tree/main/po?ref_type=heads

src/os/i18n_locales.zig

@@ -28,30 +28,30 @@
 /// we don't have a good way to determine this. We can always reorder
 /// with some data.
 pub const locales = [_][:0]const u8{
-    "zh_CN.UTF-8",
-    "de_DE.UTF-8",
-    "fr_FR.UTF-8",
-    "ja_JP.UTF-8",
-    "nl_NL.UTF-8",
-    "nb_NO.UTF-8",
-    "ru_RU.UTF-8",
-    "uk_UA.UTF-8",
-    "pl_PL.UTF-8",
-    "ko_KR.UTF-8",
-    "mk_MK.UTF-8",
-    "tr_TR.UTF-8",
-    "id_ID.UTF-8",
-    "es_BO.UTF-8",
-    "es_AR.UTF-8",
-    "pt_BR.UTF-8",
-    "ca_ES.UTF-8",
-    "it_IT.UTF-8",
-    "bg_BG.UTF-8",
-    "ga_IE.UTF-8",
-    "hu_HU.UTF-8",
-    "he_IL.UTF-8",
-    "zh_TW.UTF-8",
-    "hr_HR.UTF-8",
-    "lt_LT.UTF-8",
-    "lv_LV.UTF-8",
+    "zh_CN",
+    "de",
+    "fr",
+    "ja",
+    "nl",
+    "nb",
+    "ru",
+    "uk",
+    "pl",
+    "ko",
+    "mk",
+    "tr",
+    "id",
+    "es_BO",
+    "es_AR",
+    "pt",
+    "ca",
+    "it",
+    "bg",
+    "ga",
+    "hu",
+    "he",
+    "zh_TW",
+    "hr",
+    "lt",
+    "lv",
 };