Added KLocalizedString Wrapper.

Only added applicationDomain related methods.

tests/klocalizedcontext_tests.rs

@@ -1,4 +1,4 @@
-use ki18n_rs::KLocalizedContext;
+use ki18n_rs::klocalizedcontext::KLocalizedContext;
 use qmetaobject::prelude::*;
 mod common;
 

tests/klocalizedstring_tests.rs

@@ -0,0 +1,14 @@
+use ki18n_rs::klocalizedstring::KLocalizedString;
+use std::ffi::CString;
+
+#[test]
+fn application_domain() {
+    const APPLICATION_DOMAIN: &str = "KI18n";
+    let domain = CString::new(APPLICATION_DOMAIN).unwrap();
+
+    KLocalizedString::set_application_domain(&domain);
+    let domain = KLocalizedString::application_domain();
+    println!("{:#?}", domain);
+
+    assert_eq!(domain.to_str().unwrap(), "KI18n");
+}