Fix duplicate copy warning alert

- It was being added to the whole page everytime an answer was returned
- This meant that if **any** content on the page was copied the alert was
  being shown multiple times based on how many answers there had been
- This change will mean the alert will now only be shown when an answer
  is copied and only once

Required by #215

code/app/frontend/src/components/Answer/Answer.tsx

@@ -14,11 +14,13 @@ import supersub from 'remark-supersub'
 interface Props {
     answer: AskResponse;
     onCitationClicked: (citedDocument: Citation) => void;
+    index: Number;
 }
 
 export const Answer = ({
     answer,
-    onCitationClicked
+    onCitationClicked,
+    index,
 }: Props) => {
     const [isRefAccordionOpen, { toggle: toggleIsRefAccordionOpen }] = useBoolean(false);
     const filePathTruncationLimit = 50;
@@ -57,15 +59,16 @@ export const Answer = ({
         const handleCopy = () => {
             alert("Please consider where you paste this content.");
         };
-        document.addEventListener("copy", handleCopy);
+        var messageBox = document.getElementById("message-" + index);
+        messageBox?.addEventListener("copy", handleCopy);
         return () => {
-            document.removeEventListener("copy", handleCopy);
+            messageBox?.removeEventListener("copy", handleCopy);
         };
     }, []);
 
     return (
         <>
-            <Stack className={styles.answerContainer}>
+            <Stack className={styles.answerContainer} id={"message-" + index}>
                 <Stack.Item grow>
                     <ReactMarkdown
                         remarkPlugins={[remarkGfm, supersub]}

code/app/frontend/src/pages/chat/Chat.tsx

@@ -302,6 +302,7 @@ const Chat = () => {
                               : [],
                         }}
                         onCitationClicked={(c) => onShowCitation(c)}
+                        index={index}
                       />
                     </div>
                   ) : null}