Chore: Message to support multiple attachments (#730)

* Changes for the message to have multiple attachments
* changed the message association to attachments from has_one to has_many
* changed all the references of this association in building and fetching to reflect this change

* Added number of attachments validation to the message model

* Modified the backend responses and endpoints to reflect multiple attachment support (#737)

* Changing the frontend components for multiple attachments
* changed the request structure to reflect the multiple attachment structures
* changed the message bubbles to support multiple attachments
* bugfix: agent side attachment was not showing because of a missing await
* broken message was shown because of the store filtering
* Added documentation for ImageMagick

* spec fixes

* refactored code to reflect more apt namings

* Added updated message listener for the dashboard (#727)
* Added the publishing for message updated event
* Implemented the listener for dashboard

Co-authored-by: Pranav Raj Sreepuram <pranavrajs@gmail.com>

app/javascript/dashboard/components/widgets/conversation/ConversationCard.vue

@@ -105,15 +105,17 @@ export default {
       router.push({ path: frontendURL(path) });
     },
     extractMessageText(chatItem) {
-      if (chatItem.content) {
-        return chatItem.content;
+      const { content, attachments } = chatItem;
+
+      if (content) {
+        return content;
       }
-      let fileType = '';
-      if (chatItem.attachment) {
-        fileType = chatItem.attachment.file_type;
-      } else {
+      if (!attachments) {
         return ' ';
       }
+
+      const [attachment] = attachments;
+      const { file_type: fileType } = attachment;
       const key = `CHAT_LIST.ATTACHMENTS.${fileType}`;
       return `
         <i class="small-icon ${this.$t(`${key}.ICON`)}"></i>