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/services/agent_bots/validate_bot_service_spec.rb

@@ -1,25 +0,0 @@
-require 'rails_helper'
-
-describe AgentBots::ValidateBotService do
-  describe '#perform' do
-    it 'returns true if bot_type is not csml' do
-      agent_bot = create(:agent_bot)
-      valid = described_class.new(agent_bot: agent_bot).perform
-      expect(valid).to be true
-    end
-
-    it 'returns true if validate csml returns true' do
-      agent_bot = create(:agent_bot, :skip_validate, bot_type: 'csml', bot_config: {})
-      csml_client = double
-      csml_response = double
-      allow(CsmlEngine).to receive(:new).and_return(csml_client)
-      allow(csml_client).to receive(:validate).and_return(csml_response)
-      allow(csml_response).to receive(:blank?).and_return(false)
-      allow(csml_response).to receive(:[]).with('valid').and_return(true)
-
-      valid = described_class.new(agent_bot: agent_bot).perform
-      expect(valid).to be true
-      expect(CsmlEngine).to have_received(:new)
-    end
-  end
-end