adding firstName to newsletter

[Gabriel637]

What problem is this solving?

adding firstName to newsletter####

How should this be manually tested? Add showName, placeholderName on newsletter declaration

https://newsletter--motorolaes.myvtex.com/

Checklist/Reminders

• [ ] Updated README.md.
• [ ] Updated CHANGELOG.md.
• [ ] Linked this PR to a Clubhouse story (if applicable).
• [ ] Updated/created tests (important for bug fixes).
• [ ] Deleted the workspace after merging this PR (if applicable).

Screenshots or example usage

Type of changes

✔️	Type of Change
_	Bug fix
_	New feature
_	Breaking change
✔️	Technical improvements

[vtex-io-ci-cd[bot]]

Hi! I'm VTEX IO CI/CD Bot and I'll be helping you to publish your app! 🤖

Please select which version do you want to release:

• [ ] Patch (backwards-compatible bug fixes)

• [ ] Minor (backwards-compatible functionality)

• [ ] Major (incompatible API changes)

And then you just need to merge your PR when you are ready! There is no need to create a release commit/tag.

• [ ] No thanks, I would rather do it manually 😞

[vtex-io-docs-bot[bot]]

Beep boop :robot:

I noticed you didn't make any changes at the docs/ folder

• [ ] There's nothing new to document :thinking:
• [ ] I'll do it later :disappointed:

In order to keep track, I'll create an issue if you decide now is not a good time

• [ ] I just updated :tada::tada: