chore: Add controllers for conversation participants (#6462)

Co-authored-by: Aswin Dev P.S <aswindevps@gmail.com>
Co-authored-by: Sojan Jose <sojan@chatwoot.com>

app/views/api/v1/accounts/conversations/participants/create.json.jbuilder

@@ -0,0 +1,3 @@
+json.array! @participants do |participant|
+  json.partial! 'api/v1/models/agent', format: :json, resource: participant.user
+end

app/views/api/v1/accounts/conversations/participants/show.json.jbuilder

@@ -0,0 +1,3 @@
+json.array! @participants do |participant|
+  json.partial! 'api/v1/models/agent', format: :json, resource: participant.user
+end

app/views/api/v1/accounts/notifications/index.json.jbuilder

@@ -11,7 +11,11 @@ json.data do
       json.notification_type notification.notification_type
       json.push_message_title notification.push_message_title
       # TODO: front end assumes primary actor to be conversation. should fix in future
-      if %w[assigned_conversation_new_message conversation_mention].include? notification.notification_type
+      if %w[
+        assigned_conversation_new_message
+        participating_conversation_new_message
+        conversation_mention
+      ].include? notification.notification_type
         json.primary_actor_type 'Conversation'
         json.primary_actor_id notification.conversation.id
         json.primary_actor notification.conversation.push_event_data

app/views/mailers/agent_notifications/conversation_notifications_mailer/participating_conversation_new_message.liquid

@@ -0,0 +1,5 @@
+<p>Hi {{user.available_name}},</p>
+
+<p>You have received a new message in a conversation you are participating.</p>
+
+<p>Click <a href="{{action_url}}">here</a> to get cracking.</p>