Fix action area multiline button alignment

[noahemmet]

Checklist

• [x] All new and existing tests pass
• [x] I've read the Contribution Guidelines
• [x] I've read Change Limitations

Motivation and Context

When using a ActionArea.BarButtonItem with more than one line of text, the buttons will align improperly:

Description

This changes the stackview's alignment to . firstBaseline and horizontally centers the text:

Two lines:

One line:

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[noahemmet]

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