Add isActive style for HeaderMenu

[RianTavares]

Summary

My suggestion is a design/development enhancement.
I would like to set a boolean prop to set a style for HeaderMenu when it's active like already is made for HeaderMenuItem component.

Example of enhancement result:

Justification

As described in one item of W3 WAI (Web Accessibility Tutorials) it's important to:
"Convey menu items and their states by using color and other styling options. For example, alter the shape of a menu item, or add an icon, in addition to changing its color when it is selected."

I couldn't find a way to do this state change demonstration when a page inside the HeaderMenu is active, then I'm purposing this enhancement.

Desired UX and success metrics

Clear and consistent styling allows users to find and recognize menus more quickly. Such styling includes consistency in the behavior, appearance, and relative location on pages across a website.

I believe this enhancement will contribute to the user experience with the Header Menu as described above and, as is already done in the HeaderMenuItem component.
Also, this provides best-practice guidance on implementing accessibility for Menus.

HeaderMenuItem example:

Required functionality

No response

Specific timeline issues / requests

No response

Available extra resources

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[RianTavares]

PR created for this enhancement #9785

[matbiit]

I strongly agree with this idea! It will be have a huge impact in our solutions that using Carbon as Design System! Congrats @RianTavares for the idea and contribution!

[JulianaBerdeville]

That's such an interesting point raised by @RianTavares. It would definitely make it easier, accessible and even more accordingly with UX/UI principles and ideas.
I believe it would raise Carbon's excellency and facilitate the frontend development using Carbon as Design system.
Thanks for sharing the idea, @RianTavares! :)