fix: "/dev" fails with "Conversation id must exist" #4188

Problem:
"/dev" inside Q fails when a new conversation is started:
```
Sorry, we encountered a problem when processing your request. Amazon Q feature development request failed: Conversation id must exist before continuing
``` 

Retrying the operation is a workaround for this, and will make the conversation work as expected.

Solution:
Add `await` when creating the conversation. The missing `await` caused the error because the toolkit tried reading the `conversationId` before it was populated.

Author: jsalles

src/amazonqFeatureDev/session/session.ts

@@ -70,7 +70,7 @@ export class Session {
         // Store the initial message when setting up the conversation so that if it fails we can retry with this message
         this._latestMessage = msg
 
-        telemetry.amazonq_startConversationInvoke.run(async span => {
+        await telemetry.amazonq_startConversationInvoke.run(async span => {
             this._conversationId = await this.proxyClient.createConversation()
             span.record({ amazonqConversationId: this._conversationId })
         })