[MOOSE-292] Clean Up core/details Block

[GeoffDusome]

What does this do/fix?

This pull request cleans up and improves the core Details block in both style and configuration, focusing on code clarity, consistent styling, and better maintainability. The main changes include reorganizing and commenting the styles, updating underline behavior for summaries, and reordering the theme.json styles for clarity.

Core Details Block Cleanup and Styling Improvements:

• Added comments and reordered sections in style.pcss to clarify the purpose of style rules, and applied consistent underline styling to the summary element using mixins for both normal and hover states. [1] [2]

Configuration and Maintainability:

• Reordered the typography, spacing, and border properties for the core/details block in theme.json to improve clarity and maintainability, without changing the actual styles applied. [1] [2]
• Updated the changelog to reflect the cleanup and improvements made to the core Details block.

QA

Links to relevant issues

• Link to Issue

Screenshots/video:

• Stacked Details blocks w/ hover effect showing: https://p.tri.be/i/odZG4O

[dpellenwood]

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