feat(amazonq): enable export chat feature #6962

## Problem
Users don't have a way to export an Amazon Q chat

## Solution
Add an export icon to chat tab bar and, allow users to export
conversations from chat history. Users can choose Markdown or HTML
format

Author: avi-alpert

packages/amazonq/.changes/next-release/Feature-4b7ab0af-2fe3-4e21-be78-5fcb1896257c.json

@@ -0,0 +1,4 @@
+{
+	"type": "Feature",
+	"description": "Amazon Q chat: Click export icon to save chat transcript in Markdown or HTML"
+}

packages/core/src/amazonq/webview/ui/main.ts

@@ -973,12 +973,11 @@ export const createMynahUI = (
                     icon: MynahIcons.HISTORY,
                     description: 'View chat history',
                 },
-                /* Temporarily hide export chat button from tab bar
                 {
                     id: 'export_chat',
                     icon: MynahIcons.EXTERNAL,
                     description: 'Export chat',
-                }, */
+                },
             ],
         },
     })

packages/core/src/codewhispererChat/controllers/chat/messenger/messenger.ts

@@ -90,7 +90,7 @@ export class Messenger {
                     followUpsHeader: undefined,
                     relatedSuggestions: undefined,
                     triggerID,
-                    messageID: '',
+                    messageID: triggerID,
                     userIntent: undefined,
                     codeBlockLanguage: undefined,
                     contextList: mergedRelevantDocuments,

packages/core/src/shared/db/chatDb/util.ts

@@ -251,12 +251,11 @@ export function groupTabsByDate(tabs: Tab[]): DetailedListItemGroup[] {
 }
 
 const getConversationActions = (historyId: string): ChatItemButton[] => [
-    /* Temporarily hide export chat button from tab bar
     {
         text: 'Export',
         icon: 'external' as MynahIconsType,
         id: historyId,
-    }, */
+    },
     {
         text: 'Delete',
         icon: 'trash' as MynahIconsType,