Feat: add data type invoke (#5126)

### What problem does this PR solve?
```
Invoke agent
To be able to interact dynamically with the API, there is a customizable Data Type JSON or FormData, the default is JSON 
```

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

---------

Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

web/src/pages/flow/constant.tsx

@@ -606,6 +606,7 @@ export const initialInvokeValues = {
 }`,
   proxy: 'http://',
   clean_html: false,
+  datatype: 'json',
 };
 
 export const initialTemplateValues = {