Develop/feature/td 4916 consolidate nhs design system overrides

[frank-hee]

JIRA link

TD-4916

Description

Moved all Auth .nhsuk classes from layout.scss and common.scss into nhsuk-overrides.scss

This resulted in a lack of need for layout.scss which has been deleted

Two layouts updated to remove links to layout.css and add links to nhsuk-overrides.css

Commented nhsuk-overrides and moved some classes around to make for easier reading.

Screenshots

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Developer checks

(Leave tasks unticked if they haven't been appropriate for your ticket.)

I have:

• Run the formatter and made sure there are no IDE errors
• Written appropriate unit tests for the changes
• Manually tested my work with and without JavaScript
• Tested any Views or partials created or changed with Wave Chrome plugin and addressed any valid accessibility issues
• Updated/added documentation in Confluence and/or GitHub Readme. List of documentation links added/changed:
  • doc_1_here
• Updated my Jira ticket with information about other parts of the system that were touched as part of the MR and have to be sanity tested to ensure nothing is broken
• Scanned over my pull request in GitHub and addressed any warnings from the GitHub Build and Test checks.