Feat: Added Gupshup Messaging Adapter

[HarshitVashisht11]

What does this PR do?

This PR implement support for Gupshup in the Utopia PHP messaging library.

Fixes: appwrite/appwrite#6863

Test Plan

(Write your test plan here. If you changed any code, please provide us with clear instructions on how you verified your changes work.)

Related PRs and Issues

• 💬 Improve Appwrite Messaging with Gupshup appwrite/appwrite#6863

(If this PR is related to any other PR or resolves any issue or related to any issue link all related PR and issues here.)

Have you read the Contributing Guidelines on issues?

(Write your answer here.)

[HarshitVashisht11]

Hi @gewenyu99@wess Please review my PR

[stnguyen90]

Great PR! 🤯 Would you please attach screenshots of successful tests.

[HarshitVashisht11]

Great PR! 🤯 Would you please attach screenshots of successful tests.

Thanks for reviewing my PR. At the moment, I don't possess a Gupshup API key, which is why I'm unable to conduct testing.

[stnguyen90]

Thanks for reviewing my PR. At the moment, I don't possess a Gupshup API key, which is why I'm unable to conduct testing.

So you, nor we, have any way of confirming what you did works...

[HarshitVashisht11]

So, is there any way I can test if my code works

[gewenyu99]

@HarshitVashisht11 😅 usually those who implement the code would know how it's meant to be tested. Please include and run your tests