Add collage image link support

[galenking]

PR Summary:

Add support for links in the collage section to enable better engagement and storytelling.

Why are these changes introduced?

The collage section is great for storytelling but, without links, images are not clickable so there is no possible engagement. Being able to specify a link enables merchants to make images clickable.

Visual impact on existing themes

Images become clickable and add the hover effect if a link is specified.

Checklist

• Added PR summary for release notes
• Requested review from UX (Only for changes that are affecting the experience or perceivable visual details)
• Created a ticket for the help.shopify.com documentation team about updates to theme settings. (Internal-only task)
• Followed theme code principles
• Linted with Theme Check
• Tested on mobile
• Tested on multiple browsers
• Tested for accessibility

[translation-platform]

Localization quality issue found

The following issues may affect the quality of localized translations if they are not addressed:

• The value Link for key sections.collage.blocks.image.settings.link.label is very short. Short strings are more likely to be misunderstood by translators without context. Please provide additional context for the translators if possible.

Please look out for other instances of this issue in your PR and fix them as well if possible.

Questions about these messages? Hop in the #help-localization Slack channel.

[galenking]

Replaces #3167