Approach to integrate WhatsApp with Helpdesk

[dvdl16]

We love helpdesk, and our clients use WhatsApp.

Related issues:
#486
#909
#1622

At the moment, we use https://github.com/dvdl16/helpdesk_whatsapp with success. It enables us to:

• Receive new helpdesk tickets via WhatsApp
• Respond to customers on Helpdesk, but they receive WhatsApp messages

That said, this app does not modify the frontend at all (it uses the "email" text editor, but redirects the communications as WhatsApp messages if a custom field with a WhatsApp number is set on the HD Ticket), so there is much room for improvement.

We'd like to make the WhatsApp integration more seamless from a UI and UX perspective, so we could either:

1. Add this feature to helpdesk directly, and introduce the necessary UI changes
2. Keep helpdesk_whatsapp separate and follow this guide to modify helpdesk UI

Obviously we'd prefer to do 1, but this introduces a dependency on https://github.com/shridarpatil/frappe_whatsapp. Not everyone who uses helpdesk will use WhatsApp, but they'd still have to install the frappe_whatsapp custom app. This is similar to the recent telephony integration, but the difference is that the Frappe team controls the telephony repo. If we do not want to make frappe_whatsapp a hard dependency in helpdesk, I guess we could probably do a runtime check for the frappe_whatsapp app when the user enables the WhatsApp integration on Helpdesk Settings.

@RitvikSardana sorry to ping you directly, but I'd like to hear your thoughts?