fix: focus the workspace itself on first focus

[maribethb]

The basics

• I validated my changes

The details

Resolves

Fixes #9969

Proposed Changes

• For non-mutator, non-flyout workspaces, focuses the workspace itself on first focus, not the first block. reduces cognitive overload for screenreader users and actually reads the screenreader mode hint we added.
• No change for mutators and flyouts: focuses the first block or focusable item
• Added new tests for the above behavior
• Previously, mutator workspaces said that their focusable tree was actually the parent workspace. This causes problems. Changed it so they return themselves. See next section for details.
• Fixed an issue with a tooltip test not rendering the blocks, causing the test to pass by luck of the way previous things worked

Reason for Changes

See issue description for why the first change.

As to why the change to getFocusableTree in workspace_svg:

At an intermediate step in this PR, I had mutator workspaces also returning the workspace itself for initial focus rather than the first block. This revealed problems with getFocusableTree returning the parent workspace. It caused the escape shortcut to behave incorrectly, T to open the main workspace toolbox instead of the flyout toolbox, etc. Basically there was almost no way previously to actually put the focus on the mutator workspace itself (since mutator workspaces are never empty) and so the condition where workspace.getFocusableTree was actually hitting the mutator case never occurred. blocks on the mutator workspace did not participate in the same lie where they said that their tree was the main workspace tree. they correctly reported the mutator workspace tree.

I audited the cases where the mutator workspace being focused and getFocusableTree is called. Here are the results:

Consumer	Effect of returning parent for mutator root
FocusManager.getFocusedTree()	Wrong tree (main workspace)
globalShortcutHandler	Routes shortcuts to main workspace instead of mutator
Navigator.getTopLevelItems()	Lists main workspace blocks instead of mutator blocks
FocusManager tree-switching / highlight logic	Treats mutator root as belonging to parent tree

All of these are actually the wrong behavior. It just never mattered before since the mutator workspace was never focused.

Then after I fixed these problems, I realized it actually made more sense for mutator workspaces to continue focusing their first block, unlike the main workspace. So this again goes back to not mattering since it is very difficult to actually focus the mutator workspace again. But, this behavior is more correct, and if we change our mind in the future about focusing the first block for mutator workspaces, we can easily change that without hitting these same problems.

Test Coverage

added unit tests, fixed existing ones (that were relying on implementation details to pass). manually tested main workspaces, flyout workspaces, and mutator workspaces.

Documentation

n/a

Additional Information

[mikeharv]

Thanks for the detailed notes. Pulled and manually tested.