feat: added whatsapp-with-vonage function template in C++

[FreSauce]

What does this PR do?

Adds a function template for Whatsapp with Vonage in C++.

Test Plan

Deployed on http://653cb211876d9041c5b7.shardul.tech/
The vonage hook is working properly with the endpoint.

Related PRs and Issues

This is related to Issue #199

Have you read the Contributing Guidelines on issues?

Yes

[gewenyu99]

Hey,

Due to time constraints, I'm going to mark this PR hacktoberfest-accepted for now so you get DO's Hacktoberfest rewards. We'll continue to work with you on this issue for review and merge.

When it is merged, we'll contact you for Appwrite-specific Hacktoberfest swag.

Thanks for helping us improve Appwrite!

[gewenyu99]

Hey there! There were a lot of big PRs during this Hacktoberfest, and we wanted to give everyone ample time to collaborate with our engineering team. If you were able to merge your PRs during October, amazing. If it’s still not merged, don’t worry about it either. Either way, we’ve got your Hacktoberfest swag minted and ready to ship.

Please comment with your Discord username here so we can contact you about your shipping information to deliver your Hacktoberfest swag.

[FreSauce]

Hey, my discord id is fresauce. Also I would love to work further on this PR to get it merged

[gewenyu99]

@FreSauce Hey thanks for the help. There's some static file issues with Appwrite preventing this merge. We're working on it! Reaching out soon!