Add migration for media gallery indices

js/modules/migrations/18/index.js

@@ -0,0 +1,16 @@
+exports.run = (transaction) => {
+  const messagesStore = transaction.objectStore('messages');
+
+  [
+    'numAttachments',
+    'numVisualMediaAttachments',
+    'numFileAttachments',
+  ].forEach((name) => {
+    console.log(`Create message attachment metadata index: '${name}'`);
+    messagesStore.createIndex(
+      name,
+      ['conversationId', 'received_at', name],
+      { unique: false }
+    );
+  });
+};