Type of change

[x] New feature (non-breaking change which adds functionality)
[x] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[x] This change requires a documentation update

Description

These webhooks can only be tested locally via ngrok. Try running my command to redirect these webhooks to your localhost:3000 port

ngrok http --domain=workable-credible-mole.ngrok-free.app 3000

Three webhooks have been added
- success webhook available via /api/webhooks/vivawallet/success/
  - logic has been added to this one for verification
- failure webhook via /api/webhooks/vivawallet/failure/ -> add logic in next PR
- price webhook for transaction fees via /api/webhooks/vivawallet/price/ -> add logic in next PR
Unnecessary handlers have been deleted
- Important for frontend to know that it has not call api/orders/verify/ anymore since backend verifies it on its own via webhook
vivawallet_types.go has been added due to lots of type definitions
CreatePaymentOrder() has been improved for checkout process listing item names and (for now) correct user data for 'AnonUser'

Update README explaining how to use ngrok after running it on a different computer.
Talk about how I decided not to have a transactionID check as suggested
Fix linter warnings in next PR
Think about testing something or adding more error catches

[x] I have commented my code (or ChatGPT did), particularly in hard-to-understand areas
[ ] I have made corresponding changes to the documentation
[x] My changes generate no new warnings, neither in my IDE nor in my browser
[ ] I have added tests that prove my fix is effective or that my feature works