feat: Add support for multi-language support for Captain (#11068)

This PR implements the following features

- FAQs from conversations will be generated in account language
- Contact notes will be generated in account language
- Copilot chat will respond in user language, unless the agent asks the
question in a different language

## Changes
### Copilot Chat

- Update the prompt to include an instruction for the language, the bot
will reply in asked language, but will default to account language
- Update the `ChatService` class to include pass the language to
`SystemPromptsService`

### FAQ and Contact note generation

- Update contact note generator and conversation generator to include
account locale
- Pass the account locale to `SystemPromptsService`


<details><summary>Screenshots</summary>

#### FAQs being generated in system langauge

![CleanShot 2025-03-12 at 13 32
30@2x](https://github.com/user-attachments/assets/84685bd8-3785-4432-aff3-419f60d96dd3)


#### Copilot responding in system language

![CleanShot 2025-03-12 at 13 47
03@2x](https://github.com/user-attachments/assets/38383293-4228-47bd-b74a-773e9a194f90)


</details>

---------

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>
Co-authored-by: Pranav <pranav@chatwoot.com>

app/models/account.rb

@@ -128,6 +128,14 @@ class Account < ApplicationRecord
     }
   end
 
+  def locale_english_name
+    # the locale can also be something like pt_BR, en_US, fr_FR, etc.
+    # the format is `<locale_code>_<country_code>`
+    # we need to extract the language code from the locale
+    account_locale = locale&.split('_')&.first
+    ISO_639.find(account_locale)&.english_name&.downcase || 'english'
+  end
+
   private
 
   def notify_creation

app/models/concerns/assignment_handler.rb

@@ -48,4 +48,8 @@ module AssignmentHandler
       create_assignee_change_activity(user_name)
     end
   end
+
+  def self_assign?(assignee_id)
+    assignee_id.present? && Current.user&.id == assignee_id
+  end
 end

app/models/conversation.rb

@@ -125,6 +125,10 @@ class Conversation < ApplicationRecord
     last_message_in_messaging_window?(messaging_window)
   end
 
+  def language
+    additional_attributes&.dig('conversation_language')
+  end
+
   def last_activity_at
     self[:last_activity_at] || created_at
   end
@@ -257,10 +261,6 @@ class Conversation < ApplicationRecord
     )
   end
 
-  def self_assign?(assignee_id)
-    assignee_id.present? && Current.user&.id == assignee_id
-  end
-
   def load_attributes_created_by_db_triggers
     # Display id is set via a trigger in the database
     # So we need to specifically fetch it after the record is created