Make content fields required in post and content models (#7972)

#### What type of PR is this?

/area core
/kind improvement
/milestone 2.22.x

#### What this PR does / why we need it:

See #7967 

#### Which issue(s) this PR fixes:

Fixes #7967 

#### Does this PR introduce a user-facing change?

```release-note
None
```

ui/console-src/modules/contents/posts/PostEditor.vue

@@ -78,17 +78,8 @@ const handleChangeEditorProvider = async (provider: EditorProvider) => {
   }
 };
 
-// fixme: PostRequest type may be wrong
-interface PostRequestWithContent extends PostRequest {
-  content: {
-    raw: string;
-    content: string;
-    rawType: string;
-  };
-}
-
 // Post form
-const formState = ref<PostRequestWithContent>({
+const formState = ref<PostRequest>({
   post: {
     spec: {
       title: "",