Prevent block breadcrumb overlap with block movers for full/wide blocks

[kjellr]

#14145 introduced a new left-side placement for the block breadcrumb. This worked great at first, but when #15022 reintroduced the block movers for wide and full blocks, we realized that the new breadcrumb location overlapped with the block movers.

This PR is a potential fix for the overlap: it moves the block breadcrumb down slightly for full/wide blocks when the block movers are visible. It bumps right up against the block content itself, but I don't think this should actually cause any issues.

Before:

After:

[jasmussen]

Yep, good solution. 👍 👍

I don't see the jumpiness that shows up in your GIFs on my end, though — which is good, that jumpiness is a little weird.

Here's what I see. Master:

This branch:

Both of those are cool to me.

---

I think we should keep thinking about what to do with these hover labels, separately. Do we need them? Do they become tooltips? (Think hovering an img with a title on the web.)

[jasmussen]

Checks need to pass.

[kjellr]

Thanks for the review! I'll merge in once that test is complete. I agree, it may be worth removing the block breadcrumbs entirely. I'm not convinced they're needed anymore.

I don't see the jumpiness that shows up in your GIFs on my end, though — which is good, that jumpiness is a little weird.

Tha only shows up under a really specific circumstance: if you hover over the center-to-right area of a block, activate the block breadcrumb, and then move your mouse over to the left of the block to trigger the appearance of the block movers. 🙂