[tag tool] Medium feature to support applying a new family to the whole tag set

The inverse of https://github.com/google/fonts/issues/8506 basically :)

Another workflow, is a (medium?) feature in the tool to show **all tags** and allow rapid-fire tag data creation at the scale of **a new family**.

It should be a similar keyboard drive workflow: press `tab` (using HTML tabindex properties) to move to the next row's input box, `backspace` or `space` makes that family have a zero value (and thus disappears and doesn't appear in the CSV output), and with a desktop keyboard number pad for a right handed person, the workflow can be super fast where they tap `tab` with a left hand finger, `space` with a left hand thumb, and numbers on the numberpad with the right hand.