Add more global focus handling

[michaeljaltamirano]

We have 7 instances of the following general style pattern in this repo:

// incomplete to cover both theme.BOX_SHADOWS.focus and theme.BOX_SHADOWS.focusInner
&:focus {
    outline: none;
    box-shadow: ${({ theme }) => theme.BOX_SHADOWS

This pattern is also starting to proliferate in consumer apps, especially as we overwrite blue browser focus outlines in favor of our own style. We should consider adding this to our global stylesheets for common control components (e.g. button)