feat(admin): Add Czech language support (#5822)

- add Czech messages
- add Czech to supported languages
- add Czech to the docs

Co-authored-by: Kasper Fabricius Kristensen <45367945+kasperkristensen@users.noreply.github.com>

.changeset/cyan-chicken-roll.md

@@ -0,0 +1,5 @@
+---
+"@medusajs/admin-ui": patch
+---
+
+feat(admin-ui): Add Czech translation

packages/admin-ui/ui/src/i18n/index.ts

@@ -78,6 +78,10 @@ export const supportedLanguages = [
     locale: "ko",
     name: "한국어",
   },
+  {
+    locale: "cs",
+    name: "Čeština"
+  },
   {
     locale: "zh",
     name: "简体中文",