fix: labels for multi-statement blocks

[mikeharv]

The basics

• I validated my changes

The details

Resolves

Fixes #9617

Proposed Changes

When focusing a block with multiple statement inputs (or moving to one), the block label will now:

• Only include labels from inputs up to the first statement, inclusive.
• Include a has %1 branches label indicating the number of statement inputs.
• No longer include has inputs as it's redundant and confusing.

Move announcements will similarly use the new shorter label, but will continue to not add an input/branch count label:

Reason for Changes

From the linked issue:

The label for the block should only include the text of the first branch, plus the number of branches. e.g. "if, has 3 branches"

Test Coverage

Tests were added to ensure that block labels are computed as expected for multi-statement blocks.