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>

app/services/agent_bots/validate_bot_service.rb

@@ -1,38 +0,0 @@
-class AgentBots::ValidateBotService
-  pattr_initialize [:agent_bot]
-  def perform
-    return true unless agent_bot.bot_type == 'csml'
-
-    validate_csml_bot
-  end
-
-  private
-
-  def csml_client
-    @csml_client ||= CsmlEngine.new
-  end
-
-  def csml_bot_payload
-    {
-      id: agent_bot[:name],
-      name: agent_bot[:name],
-      default_flow: 'Default',
-      flows: [
-        {
-          id: SecureRandom.uuid,
-          name: 'Default',
-          content: agent_bot.bot_config['csml_content'],
-          commands: []
-        }
-      ]
-    }
-  end
-
-  def validate_csml_bot
-    response = csml_client.validate(csml_bot_payload)
-    response.blank? || response['valid']
-  rescue StandardError => e
-    ChatwootExceptionTracker.new(e, account: agent_bot&.account).capture_exception
-    false
-  end
-end