[FEATURE] Support WhatsApp CloudAPI channel

[a5r0n]

WhatsApp CloudAPI now is publicly available.
https://developers.facebook.com/blog/post/2022/05/19/whatsapp-cloud-based-api/

using the official meta service can reduce some third party costs..

[slvnperron]

@a5r0n I agree! We plan to add more channels in the coming months including WhatsApp. In the meantime, we would welcome a community contribution!

[rsaisankalp]

Can you detail out how to add support for multiple channels

[arthurvenicio]

Have more details about cloud api support?

[firehist]

Hey guys,
I didn't find out how to test a new channel integration ?
I run the tilt or serve command.
Then I also should point my botpress OSS to this messaging server, how can I do it ?!

[ivarunseth]

Hi @slvnperron,
I have raised a PR for this feature request.
Please review.

#676