Command Palette: remove duplicated "group" related command

[annezazu]

Pulled from the FSE Outreach Program's Final Touches call for testing:

“Group” and “Transform to Group” commands do the same. Hiding one of them could make it clearer.

@richtabor is there any reason for the duplication?

[richtabor]

Technically, the root of this is because the paragraph block (and many others) have a transform to group, while the "Group" option is also available in the block toolbar options menu — and these block-related commands are pulling available transforms and block options.

It's a bigger change, but I lean towards removing the generic group transform (which doesn't really transform a block, but "group" it). Transforming is more about changing a block into another, not grouping (which we have the option for persisting in the block options for all blocks). Even the transform to columns control is not well suited; you end up with the block in a single column, which feels unresolved.