[UI][Tabs] Prevent tab focus on mousedown

[SimoTod]

Currently a tab gets the focus when you receive the mousedown event instead of the full click.
This is different from how tabs usually work everywhere else (including Tailwind Headless UI that fixed it with this PR: tailwindlabs/headlessui#1192).

Unfortunately, it's not easily testable because cypress doesn't behave that way but chrome and firefox do.

This seem to cause some interoperability issues with x-dialog too: #4230 (reply in thread) (The OP didn't provide an example though).

[calebporzio]

Ah this makes total sense and the mousedown prevention listener is a nice solution - I didn't know that would prevent focus but it makes sense.

I'm gonna use that in other situations too.

Thanks simone!