feat(user-profile): Theme toggle improvements

[9inpachi]

Hi,

Used more natural (and intuitive) icons for the light and dark modes. And made it so the dropdown doesn't close on changing the theme since users often want to quickly toggle and check between the two modes (like myself).

Before:

After:

Let me know if this is undesired. :)

Thanks.

[adamnel]

I'd avoid changing the standard interaction for a menu to suit a specific context - it's more important that the item behaves consistently than that it saves a click in this specific scenario.

With respect to the icon choice, I think we do have an opportunity to tweak it, but I'd follow Google's own decisions here:

These are visible in the footer of https://support.google.com/

[9inpachi]

@adamnel I see. That makes a lot of sense.
I will close the PR then.
Thanks.