Remove positional and level information for blocks in screen reader output

[BenHenning]

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Problem

Discussion this week suggested that screen reader output should be simplified and not need positional information.

Separately, treeitems have caused compatibility issues on Safari with VoiceOver.

Request

Remove Workspace's treeitem usage for blocks, though the version for Flyout can maybe be kept (more thought is needed there).

Alternatives considered

No response

Additional context

No response