Expose Explain Commit in more places

[d13]

Description

Expose the commit explanation feature in more places

• remove the existing "Explain Changes" button (and view) from commit details
• add an "Explain" button to the bottom of the commit message element
• allow users to explain a single commit from the graph via context menu
• allow users to explain commits via a command in the command palette (similar to changelog generation flow)
• allow users to explain commits from the commits view
• allow users to explain commits from Search & Compare

[github-actions]

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