feat: Implement UI for Agent Bots in settings and remove CSML support (#11276)

- Add agent bots management UI in settings with avatar upload
- Enable agent bot configuration for all inbox types
- Implement proper CRUD operations with webhook URL support
- Fix agent bots menu item visibility in settings sidebar
- Remove all CSML-related code and features
- Add migration to convert existing CSML bots to webhook bots
- Simplify agent bot model and services to focus on webhook bots
- Improve UI to differentiate between system bots and account bots

## Video 





https://github.com/user-attachments/assets/3f4edbb7-b758-468c-8dd6-a9537b983f7d

---------

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

spec/models/agent_bot_spec.rb

@@ -39,4 +39,23 @@ RSpec.describe AgentBot do
       expect(message.reload.sender).to be_nil
     end
   end
+
+  describe '#system_bot?' do
+    context 'when account_id is nil' do
+      let(:agent_bot) { create(:agent_bot, account_id: nil) }
+
+      it 'returns true' do
+        expect(agent_bot.system_bot?).to be true
+      end
+    end
+
+    context 'when account_id is present' do
+      let(:account) { create(:account) }
+      let(:agent_bot) { create(:agent_bot, account: account) }
+
+      it 'returns false' do
+        expect(agent_bot.system_bot?).to be false
+      end
+    end
+  end
 end