Laydibird/UI: select location when you change tab

[elcuco]

When you move to another tab, other browsers automatically select the location editor - so you can navigate into a new page. Lets do this.

Another hack I added here - when we just open a new tab - also select the location edit (this was tricky since we load a new page on new tabs)

This PR, is somewhat based on https://github.com/SerenityOS/ladybird/pull/112