USWDS-Site: Add consolidated changelog to what's new page

[amyleadem]

Summary

Added a consolidated changelog to the What's new page. This allows design system users know what's changed across the design system.

Note

This PR updates the solution created in PR #3091. This PR:

• Updates the page structure to match the prototype created in [Prototype] USWDS-Site: What's new page round 2 #3094
• Utilizes reusable YAML variables to set the page on the changelog entries instead of manually setting this value in each entry.

Related issue

Closes #1829

Preview link

• What's new page changelog
• Changelog page

Problem statement

It's important that design system users know how the design system is changing. We have changelogs on individual pages, but there's currently no way to see all the changes in a single view.

There've been many changes to the design system in the last couple weeks, and we've recently added content change alerts to content affected by recent executive orders and policy guidance.

Solution

Add a view to the What's New page so design system users know what's changed across the design system.

This PR adds a consolidated changelog to our What's New page so design system users can better keep up to date with these changes. This new view will show the last 250 changes to the design system.

Major changes

• Created a new consolidated changelog feed that pulls in data from all changelog files and sorts them in reverse chronological order
• Added new "affects" tags: isAddition, isRemoval, affectsPageContent, affectsLinks and added these tags to appropriate changelog entries
• Added "page" data for the consolidated changelog
  • Note: We used reusable YAML variables to set the value for "page" for each changelog entry.

Testing and review

• Confirm the entries in the consolidated changelog are displaying the expected data
  • Confirm all changelog entries display the appropriate "page" name
• Confirm the consolidated changelog is readable at all screen widths on both the what's new page and the USWDS changelog page
• Confirm the new "affects" tags make sense, display appropriately, and have been added to the appropriate changelog entries
• Confirm no regressions in the changelogs on other pages
• Confirm that there is not a better alternative for setting the page title in each changelog entry
• Confirm the updated README content is accurate

[amyleadem]

Note

Added hideTagsTablet here because the in-page nav on the what's new page makes the table too narrow to be readable at tablet widths. This hides all the "Affects" column at tablet widths but still shows the breaking tag in the description column. This matches the existing behavior in changelog-table.html.

On the changelog page, there is more room so the tags remain visible at all widths.