refactor: prepare for sfc support

wip: sfc loader

feat(sfc): able to load sfc

Author: antfu

examples/sfc/src/App.vue

@@ -11,7 +11,7 @@
   </div>
 </template>
 
-<i18n>
+<i18n locale='en'>
 {
   "en": {
     "hello": "hello world!"

examples/sfc/src/CompA.vue

@@ -1,5 +1,8 @@
 <template>
-  <p>A: {{ $t('hello') }}</p>
+  <div>
+    <p>Language: {{ $t('language') }}</p>
+    <p>A: {{ $t('hello') }}</p>
+  </div>
 </template>
 
 <i18n>
@@ -13,6 +16,14 @@
 }
 </i18n>
 
+<i18n lang='yaml' locale='en'>
+language: English
+</i18n>
+
+<i18n lang='yaml' locale='ja'>
+language: 日本語
+</i18n>
+
 <script>
 export default {
   props: {