Use Hosted accent colour for lightbox divider

[cemms1]

What does this change?

• Moves the accent colour overrides function from the article layout to a helper function for easier reuse
• Extracts the hosted content scroll padding to the palette overrides function
• Uses the palette overrides in the HostedContentPage level instead of the layout level below - this enables us to use the palette override colours for the lightbox divider colour since Lightbox is used at this level
• Uses the accent colour of the hosted content campaign for the lightbox divider
• Ensures the other palette colours using the accent colour come through to the HostedGalleryLayout component
• Adds a Storybook variation for hosted content with accent colour
• Adds a new Storybook decorator with hosted palette overrides based on the accent colour of the campaign
  • Uses this within Hosted content stories

Why?

We want the lightbox divider colour to be the same as the accent colour of the hosted content campaign.

This is part of the Hosted Content migration from frontend to DCR

Screenshots

Before	After

[github-actions]

Deploy build 28582 of dotcom:rendering-all to CODE

All deployment options

• Deploy build 28582 of dotcom:rendering-all to CODE
• Deploy parts of build 28582 to CODE by previewing it first
• What's on CODE right now?

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From guardian/actions-riff-raff.

[github-actions]

Deploy build 1983 of dotcom:ab-testing to CODE

All deployment options

• Deploy build 1983 of dotcom:ab-testing to CODE
• Deploy parts of build 1983 to CODE by previewing it first
• What's on CODE right now?

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From guardian/actions-riff-raff.