Implement 'transitional' crown assets in Frontend (v5.0)

[querkmachine]

What

Implement a set of 'transitional' crown assets in GOV.UK Frontend v5.0.

These assets will use the new formats decided in #4175 but continue to show the St. Edward's crown.

Why

There is a reasonable chance that we will not have permission to launch the Tudor crown until after we intend to launch GOV.UK Frontend 5.0.

To mitigate this, we will make as many changes to the code and assets as possible in 5.0 whilst maintaining the St. Edward's crown. We will then switch to the Tudor crown in a subsequent release. See #4178.

Who needs to work on this

• Developers

Who needs to review this

• Developers
• Designers
• Accessibility specialist

Done when

Tasks

Preview Give feedback

1. Inline SVG graphic has been implemented in Header component
2. Accessibility considerations for logo's change in have been made (e.g. removal of role="presentation")
3. Sass has been updated to account for the new lockup (link hover styles, product name integration, etc.)
4. Favicon and web sharing graphics have been replaced