feat: Improve Captain interactions, activity messages (#11493)

Show captain messages under the name of the assistant which generated
the message.

- Add support for `Captain::Assistant` sender type
- Add push_event_data for captain_assistants
- Add activity message handler for captain_assistants
- Update UI to show captain messages under the name of the assistant
- Fix the issue where openAI errors when image is sent
- Add support for custom name of the assistant

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>

spec/enterprise/models/message_spec.rb

@@ -0,0 +1,25 @@
+require 'rails_helper'
+
+RSpec.describe Message do
+  let!(:conversation) { create(:conversation) }
+
+  it 'updates first reply if the message is human and even if there are messages from captain' do
+    captain_assistant = create(:captain_assistant, account: conversation.account)
+    expect(conversation.first_reply_created_at).to be_nil
+
+    ## There is a difference on how the time is stored in the database and how it is retrieved
+    # This is because of the precision of the time stored in the database
+    # In the test, we will check whether the time is within the range
+    expect(conversation.waiting_since).to be_within(0.000001.seconds).of(conversation.created_at)
+
+    create(:message, message_type: :outgoing, conversation: conversation, sender: captain_assistant)
+
+    expect(conversation.first_reply_created_at).to be_nil
+    expect(conversation.waiting_since).to be_within(0.000001.seconds).of(conversation.created_at)
+
+    create(:message, message_type: :outgoing, conversation: conversation)
+
+    expect(conversation.first_reply_created_at).not_to be_nil
+    expect(conversation.waiting_since).to be_nil
+  end
+end