Clarify multi-selection groups

[mtias]

Consider showing how many blocks are selected in a multi-selection instance to help clarify that movers, etc, apply to all blocks.

Also, transform tools are confusingly placed at the top:

They should appear there only if the user has chosen to have a fixed toolbar, otherwise it should show by the blocks.

[karmatosed]

I like this and showing how many makes a lot of sense.

Side point, a thought buzzing around my head is maybe to only show transforms on ellipsis. I just am not sure they need to be in both places right now. If you had that by the block you'd be experiencing some visual complexity.

[ZebulanStanphill]

Notably, it was decided to only show transforms in the block toolbar and not in the ellipsis menu, so showing the transform options in the ellipsis menu is no longer a good option since it would introduce an inconsistency, as well as not work with the upcoming redesign of the transform button to use a UI that resembles the block inserter.

[notnownikki]

Working on this in #7635

[ZebulanStanphill]

#7891 has moved the block toolbar to appear inline for a multiple block selection. Notably, it does not stay on-screen when you scroll down past the first block. See #7962.

[youknowriad]

Going to close this as the multi-selection UI changed and the switcher is by the block now while the number of blocks is shown in the sidebar