…erve all visual interactions

This is a big commit with a large potential for bugs. Think of this as a spike or POC for now. There'll be a lot to address. Some general TODOs:
- [ ] Refactor shared code between empty-block-inserter and selected-block-tools
- [ ] More explicitly pass the popover slot and content ref into the SelectedBlockTools
- [ ] Shortcut/keystrokes for returning from the toolbar to where the cursor was before moving into the toolbar
- [ ] Inline Tools either move to the top toolbar or get inserted into the main block toolbar (think image caption formatting tools)
- [ ] Visual styles for the top toolbar

…oolbar

…over setting

…ock.

Still more todo. This shouldn't go to the last focused block but the last _selection_ which will be a bit more work. Probably best to refactor how it works within use-tab-nav. Maybe turn it into a hook or something that can have centralized logic.

It's not working for buttons that contain dropdowns, such as the align or options buttons. The dropdown toggle is intercepting the escape keypress and not letting it bubble.

…n via onChildrenKeyDown passed to NavigableToolbar

Note: Due to the use of portals in the toolbar slots, consistently handling event listeners cleanly is difficult.

This method adds event listeners to all children of a toolbar if a `onChildrenKeyDown` prop is passed to the <NavigableToolbar /> via a querySelectorAll( '[data-toolbar-item="true"]' ) on the NavigableToolbar ref, then applying an addEventListener to all the returned buttons.

Pros: Event listener is applied and handled in one location.
Cons: Feels yucky. Feels like crossing our fingers and hoping it works consistently, which it might.

…edblock toolbar, attached to the NavigableToolbar

This method requires forwarding a ref from the editor level down to the navigable toolbar so that the escape unselect shortcut can be blocked and the navigable toolbar event listener will still fire.

Blocking the global escape event shouldn't be necessary, but we have a combination of a few things all combining to create a situation where:
- Because the block toolbar uses createPortal to populate the block toolbar fills, we can't rely on the React event bubbling to hit the onKeyDown listener for the block toolbar
- Since we can't use the React tree, we use the DOM tree which _should_ handle the event bubbling correctly from a `createPortal` element.
- This bubbles via the React tree, which hits this `unselect` escape keypress before the block toolbar DOM event listener has access to it.

…-controls slot

If remove the bubblesVirtually from the block-controls slot, then the event will bubble in the DOM as normal (instead of the React Tree only since bubblesVirtually uses createPortal for the fills). This means we could handle the event without any forwardRefs as we don't need to block the escape shortcut keypress event from the React Tree.

However, we assume bubblesVirtually was made for a reason. So, we're unsure if something would break.

…lds in editor.

… by default on escape keypress

Not committed to this, but it does work since we've removed bubblesVirtually from the toolbar slots and the inline rich editor doesn't use slots for its tools. I like that this brings this behavior by default to the toolbars, but unsure about if it's a good idea overall.