feature: Allow changing the contact for a conversation

[jordan-brough]

We'd like to be able to change the contact for a conversation.

Recent example for us:

• Customer emailed our CEO
• Our CEO replied and cc'd our support (Chatwoot) email address
• Chatwoot thinks the conversation was started by our CEO, when it should really be the customer

If we have customer-based actions, or automations, or filtering they will not work correctly. We don't want to edit the contact or merge contact because the contact is a valid contact (our CEO0. We'd like to enable agents to switch the contact for the conversation.

Is this something y'all have considered, or would be willing to accept a PR for? (I searched for previous issues/conversations but couldn't find any).

[pranavrajs]

@jordan-brough Happy to take a PR. I guess this is similar to https://github.com/chatwoot/chatwoot/issues/5303