tools/check-messages-en: Check for straight quotes in messages

We caught all the straight quotes in f8351f0, but it looks like
one crept in after that. Add this check so it doesn't happen again.

Author: chrisbobbe

src/chat/InvalidNarrow.js

@@ -27,7 +27,7 @@ type Props = $ReadOnly<{|
 export default function InvalidNarrow(props: Props): Node {
   return (
     <View style={styles.container}>
-      <ZulipTextIntl style={styles.text} text="That conversation doesn't seem to exist." />
+      <ZulipTextIntl style={styles.text} text="That conversation doesn’t seem to exist." />
     </View>
   );
 }

static/translations/messages_en.json

@@ -119,7 +119,7 @@
   "Username": "Username",
   "Password": "Password",
   "Why not start the conversation?": "Why not start the conversation?",
-  "That conversation doesn't seem to exist.": "That conversation doesn't seem to exist.",
+  "That conversation doesn’t seem to exist.": "That conversation doesn’t seem to exist.",
   "Request timed out.": "Request timed out.",
   "Sign in with {method}": "Sign in with {method}",
   "Invalid input": "Invalid input",

tools/check-messages-en

@@ -165,6 +165,20 @@ function getPossibleUiStrings(possibleUiStringFilePaths) {
 }
 
 function main() {
+  // Mobile's style is to use curly quotes. They look nicer, but also: since
+  // v3, react-intl uses the single straight quote as an escape character:
+  //   https://formatjs.io/docs/intl-messageformat/#features
+  const messagesWithStraightQuotes = Object.values(messages_en).filter(message =>
+    /['"]/.test(message),
+  );
+  if (messagesWithStraightQuotes.length > 0) {
+    console.error(
+      'Found messages in static/translations/messages_en.json that have straight quotes. Please use smart quotes: “” and ‘’.',
+    );
+    console.error(messagesWithStraightQuotes);
+    process.exit(1);
+  }
+
   const possibleUiStrings = getPossibleUiStrings(getPossibleUiStringFilePaths());
 
   // Check each key ("message ID" in formatjs's lingo) against