Add optional scheme and label parameters to the category element - Atom feeds

[mistrynilesh]

Describe the solution you'd like
It would be nice to allow the passing of scheme and label parameters to the Category element.
Also, Category element should be available for Entry element (i.e. https://validator.w3.org/feed/docs/atom.html#optionalFeedElements).

We don't have the option to pass scheme and label parameter in the addCategory function.

For example -

<entry>
.........
<category scheme="topic" term="491"/>
</entry>

Thanks