Implement split button component

[dcrjodle]

Summary

Request to implement a split button component for the UI library.

Additional Context

The image shows an example of a split button pattern where a primary action button (e.g., "Reply") is paired with a dropdown trigger to reveal additional related actions ("Reply All", "Forward", "Reply & Delete").

This is a common UI pattern used in email clients and other applications where users need quick access to a primary action with secondary options available via dropdown.

Reference

Slack thread

Reported by Mikael Rinne

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