Add link to `ui.tab` to direct user to external URL when clicked on

#### Is your feature request related to a problem? Please describe

I have a bunch of tabs which I use for navigation. I want the last one to link to documentation which is an external URL. However, I don't see a way to open an external URL using a tab.

#### Describe the solution you'd like

Ideally, the ability to specify an external URL in the tab, maybe a property called `link` just like a button.

#### Describe alternatives you've considered

For now, external URLs were opened by setting inline script to `f'window.open("{external_url}");'`. However, this is not ideal since the page has to be re-rendered. Do mention if there are any _more elegant_ solutions to this.

Start at the ui.tab API and compare it with the button link behavior mentioned in the issue. Check how tab clicks and the current inline window.open workaround are handled; done means a tab can open an external URL without requiring a page rerender.

Written by the indexing model from the issue text.