Nested block toolbars do not work properly with "Fix Toolbar to Top" setting

[ZebulanStanphill]

Issue Overview

When you enable the "Fix Toolbar to Top" setting, the toolbars of nested blocks do not display in the top bar properly, and are still shown at the blocks themselves rather than just in the top bar.

Steps to Reproduce (for bugs)

1. Enable the "Fix Toolbar to Top" setting.
2. Insert a Columns block.
3. Insert an Image block and a Paragraph block into the Columns block.
4. Select the Paragraph block.
5. Notice that the toolbar appears both at the block and in the top bar.
6. Select the Image block.
7. Notice that the Paragraph block toolbar settings are shown in the top bar in place of the Image block toolbar settings, except for the transform button on the left.
8. Select the Paragraph block.
9. Notice that the Image block toolbar settings are shown in the top bar in place of the Paragraph block toolbar settings, except for the transform button on the left.

Expected Behavior

Nested blocks should have their toolbars display only in the top bar when the "Fix Toolbar to Top" setting is enabled.

Current Behavior

When you enable the "Fix Toolbar to Top" setting, the toolbars of nested blocks are shown in both the top bar and at the blocks themselves. Selecting a block and then selecting another block will show the toolbar settings of the previously-selected block in the top bar, except for the transform button on the left.