feat: add save and send functionality for user message

Adds a "Save" button to the edit message form in Playground, allowing users to save changes without immediately submitting them. This also introduces a new `isSend` flag to the `onEditFormSubmit` prop, enabling developers to control whether a message should be sent immediately or saved for later submission. This enhances flexibility and user control during the message editing process.

src/components/Option/Playground/PlaygroundChat.tsx

@@ -46,8 +46,8 @@ export const PlaygroundChat = () => {
             isProcessing={streaming}
             isSearchingInternet={isSearchingInternet}
             sources={message.sources}
-            onEditFormSubmit={(value) => {
-              editMessage(index, value, !message.isBot)
+            onEditFormSubmit={(value, isSend) => {
+              editMessage(index, value, !message.isBot, isSend)
             }}
             onSourceClick={(data) => {
               setSource(data)