Explore a more systematic approach to interactions that should / could hide the block toolbar

[scruffian]

What problem does this address?

When manipulating things via the Inspector Controls, the Block Toolbar can often obscure the block in a frustrating way. This is evident for the spacing visualizer: #45131

However the same is also true for other manipulations that happen in the Block Inspector, and also things like canvas resizing.

What is your proposed solution?

We should look for a more systematic approach to defining when the Block Toolbar should be hiden/shown.

[jasmussen]

Would love to see this happen also during drag and drop events. For example I might have a paragraph selected, showing its block toolbar, and when I drag an image from my desktop to be above the paragraph, the toolbar could fade out until I've added the image.

[talldan]

Just a note that this was fixed for the visualizers. There are new showBlockInterface and hideBlockInterface actions for hiding the toolbar.

I'm extending it to also hide the block outline in #45056.

At the moment these actions are locked/private apis as there's a lot of overlap with the startTyping/stopTyping actions that do the same thing. We need to figure out how to consolidate the two APIs.

There's no reason not to start using it in a few more places though.