Add option to set 'Reply to all' as default in Helpdesk settings

[pandafy]

Is your feature request related to a problem? Please describe.

Currently, when replying to a ticket in Helpdesk, the default behavior is to reply only to the original ticket creator. If there are multiple participants or interested parties on a ticket, agents have to manually select 'Reply to all' each time. This increases the chance of communication gaps when an agent forgets to include all parties by default.

Describe the solution you'd like

Introduce an option in the Helpdesk settings (a switch, flag, or boolean) that allows administrators to set the default reply behavior. When enabled, the 'Reply to all' option becomes the default action for agents responding to tickets, ensuring all involved parties are included automatically in responses.

Describe the alternatives you've considered

Currently, agents can manually choose 'Reply to all', but it's easy to forget. A possible alternative is a user prompt if not all parties are included, but a configurable default setting is more seamless.

Additional context

This feature would help in environments where multiple people or departments are involved in tickets and seamless communication is critical. It would be helpful to have this as a simple toggle in Helpdesk settings, making it easy for organizations to control their preferred workflow.