feat: Add Public APIs for API Channel (#2375)

app/controllers/public/api/v1/inboxes/conversations_controller.rb

@@ -0,0 +1,24 @@
+class Public::Api::V1::Inboxes::ConversationsController < Public::Api::V1::InboxesController
+  def index
+    @conversations = @contact_inbox.hmac_verified? ? @contact.conversations : @contact_inbox.conversations
+  end
+
+  def create
+    @conversation = create_conversation
+  end
+
+  private
+
+  def create_conversation
+    ::Conversation.create!(conversation_params)
+  end
+
+  def conversation_params
+    {
+      account_id: @contact_inbox.contact.account_id,
+      inbox_id: @contact_inbox.inbox_id,
+      contact_id: @contact_inbox.contact_id,
+      contact_inbox_id: @contact_inbox.id
+    }
+  end
+end