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

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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>

db/migrate/20250410061725_convert_csml_bots_to_webhook_bots.rb

@@ -0,0 +1,13 @@
+class ConvertCsmlBotsToWebhookBots < ActiveRecord::Migration[7.0]
+  def up
+    # Find all CSML bots (bot_type = 1) and convert them to webhook (bot_type = 0)
+    AgentBot.where(bot_type: 1).find_each do |bot|
+      bot.update(bot_type: 0, bot_config: {})
+    end
+  end
+
+  def down
+    # This migration is not reversible - we've removed CSML support
+    raise ActiveRecord::IrreversibleMigration
+  end
+end