feat: Introduce allowed_domains for web widget (#12450)

We wanted to provide an option for users to specify the domains on which
they can show the website. The rest of the sites shouldn't see the
widget at all.

It's not possible generally through Origin because you can't get Origin
when loading via an iframe. What I've done is add frame ancestors for
the domains specified in allowed domains. I hope this solves most of the
problems.

This is added in a way that it won't affect existing widgets. Only If
they have configured allowed domains, it will start blocking. Otherwise,
it would follow the previous behavior without any changes.

This change supports called wild card domains as well. You can add a
comma‑separated list of domains, either wild card or regular domains.


---

To test, deploy to staging. Call the following API to update the
allowed_domains list.

```
URL: PATCH /api/v1/accounts/<account-id>/inboxes/<inbox-id>

Payload:
{
   "channel": { "allowed_domains": "*.chatwoot.dev,chatwoot.com" }
}

```



Fixes https://github.com/chatwoot/chatwoot/issues/1985

app/models/channel/web_widget.rb

@@ -3,6 +3,7 @@
 # Table name: channel_web_widgets
 #
 #  id                    :integer          not null, primary key
+#  allowed_domains       :text             default("")
 #  continuity_via_email  :boolean          default(TRUE), not null
 #  feature_flags         :integer          default(7), not null
 #  hmac_mandatory        :boolean          default(FALSE)
@@ -31,7 +32,7 @@ class Channel::WebWidget < ApplicationRecord
 
   self.table_name = 'channel_web_widgets'
   EDITABLE_ATTRS = [:website_url, :widget_color, :welcome_title, :welcome_tagline, :reply_time, :pre_chat_form_enabled,
-                    :continuity_via_email, :hmac_mandatory,
+                    :continuity_via_email, :hmac_mandatory, :allowed_domains,
                     { pre_chat_form_options: [:pre_chat_message, :require_email,
                                               { pre_chat_fields:
                                                 [:field_type, :label, :placeholder, :name, :enabled, :type, :enabled, :required,