Block Styles UI: Add tooltip on hover

[shaunandrews]

With the new UI for block styles in the inspector sidebar, longer style names have been truncated. The full style name does appear in the preview flyout, but it might be helpful to also show a tooltip near the button with the full style name:

[ramonjd]

Just to loop back as to when and why we added the ellipsis:

#34522 (comment)

Here I'm wrapping each button in a <Tooltip />

We could do it for all or for Buttons whose label lengths are > 12, which is the point at which the text control truncates.

[shaunandrews]

I'd expect the tooltip to appear (below the button) regardless of the length of the label; Otherwise it feels strangely inconsistent.

My only bit of feedback here is around the position of the tooltip; It appears to "touch" the button and can end up looking a little awkward. I don't think its really tied to this issue, so I created a new one in #37076.