Move language handling into languageHandler

src/languageHandler.tsx

@@ -56,6 +56,15 @@ export function newTranslatableError(message: string) {
     return error;
 }
 
+export function getUserLanguage(): string {
+    const language = SettingsStore.getValue("language", null, /*excludeDefault:*/true);
+    if (language) {
+        return language;
+    } else {
+        return normalizeLanguageKey(getLanguageFromBrowser());
+    }
+}
+
 // Function which only purpose is to mark that a string is translatable
 // Does not actually do anything. It's helpful for automatic extraction of translatable strings
 export function _td(s: string): string {