feat(api): Allow style tags and attributes in the In-App & Email Editor

[rifont]

What change does this PR introduce?

Adds preservation of style tags and attributes through the sanitize-html library configuration options. In-App and Email HTML content now preserves style tags and attributes on save.

Why was this change needed?

Closes NV-3026

Other information (Screenshots)

In-App Editor Update: Preserving Style Tags and Attributes - Watch Video

[linear]

NV-3026 On update button click, css styles are removed in in-app template editor

Try these content

<style>
p {color: red;}
</style>
<p>This is a paragraph.</p>

or

<p style="color:red;">A red paragraph.</p>