Grtlv 398 update article listing page template cptpp

[FoxJamie16]

What

Article Listing Pages:
Previously in article listing pages, the list was auto-generated in-template to create links to all child articles of each listing page. This used unsuitable styling and gave content editors no facility for modifying the order of items, changing the text used for the links, or adding leading text/headings to split up list items.

This PR introduces new styling and a streamfield to create the link list, along with a 'use_updated_link_format' toggle to allow the content editors time to transition to the new format. The toggle can be removed once all article pages have been transitioned by content editors. The streamfield allows content editors to add any amount of rich text and link blocks in any order to a listing page, allowing customisation of the list. As a part of the styling changes the hero image was removed following design feedback.

Article Pages:
Remove a css class hiding the 'related content' list on mobile devices.
Social media html import and positioning changing to use updated icons.
Page spacing altered to better conform with great container usage.

Why

The CPTPP agreement is getting ratified soon, and there will be links posted by marketing to new market articles of these types. Content and design both agree that a redesign was needed, and content wanted additional options to customise article listings with headings and custom links.

Screenshots:

Before:

Listing Page:

Article Page:

After:

Listing Page:
https://github.com/user-attachments/assets/5860642a-0a7b-4f7a-98cb-4604417e0aee

Article Page:

Tick or delete as appropriate:

Workflow

• Ticket exists in Jira https://uktrade.atlassian.net/browse/GRTLV-398
• Jira ticket has the correct status.
• A clear/description pull request messaged added.

Reviewing help

• Explains how to test locally, including how to set up appropriate data.- wagtail admin -> markets - > create listing page -> create article page
• Includes screenshot(s) - ideally before and after, but at least afte
• Documentation has been updated as necessary

Housekeeping

• I have checked that my PR is using the latest package versions of: great-components, directory-constants, directory-healthcheck, directory-validators, directory-components, directory-api-client, directory-ch-client, django-staff-sso-client, directory-forms-api-client, directory-sso-api-client, sigauth

Security

• Frontend assets have been re-compiled
• Checked for potential security vulnerabilities
• Ensured any sensitive data is handled appropriately

Performance

• Evaluated the performance impact of the changes
• Ensured that changes do not negatively affect application scalability.

Merging

• This PR can be merged by reviewers. (If unticked, please leave for the author to merge)