Refactor code and test to use @sendgrid/mail

[AkashM398]

Description

This PR refactors the "forward-message-sendgrid" example's code and test to use the @sendgrid/mail library instead of the got library. The got library has been removed from the package.json file, and @sendgrid/mail has been added in its place. This change was made for the following issue, refer to it for more information - Issue #419

The following changes were made:

• Modified the forward-message-sendgrid.protected.js file to use @sendgrid/mail instead of got.
• Modified the forward-message-sendgrid.test.js file to use @sendgrid/mail instead of got used for mocking the requests to Sendgrid REST API.

These changes have been tested and the updated test suite is passing. Please review and let me know if there are any questions or concerns.

Checklist

• I ran npm test locally and it passed without errors.
• I acknowledge that all my contributions will be made under the project's license.

Related issues

#419

[cmsunu28]

Hi, @AkashM398 . Thanks for your incredible patience-- we are in the process of migrating CodeExchange and Twilio Function Templates to a new team. Could you let me know if you still need this merged? It looks like you have a conflict in package-lock.json.