feature: Text Image Block

[jbmoelker]

Changes

• Adds a Text Image Block with a Structured Text, Image and Layout field.
• Reuses Text and Image implementation from TextBlock and ImageBlock.
• Adds side-by-side layout (text-image or image-text) used on wider screens.
• Uses @container component query so layout works regardless of component context.

Note: this PR is based on feat/extensible-structured-text so it could use TextBlock/Text.astro. So #81 should be merged first.

Associated issue

N/A

How to test

1. Open preview link
2. Navigate to /en/english-only/
3. Review the TextImageBlock in action
4. Add a Text Image Block to the home page or a generic page in the CMS
5. Review the page you've just added the block to

Checklist

• [x] I have performed a self-review of my own code
• [x] I have made sure that my PR is easy to review (not too big, includes comments)
• I have added/updated tests to prove that my feature works (if not possible please explain why)
• I have made changes to the README and if the change affects the project setup (npm commands changed, new service added, environmental variable added)
• I have added a decision log entry if the change affects the architecture or changes a significant technology
• [x] I have notified a reviewer

[cloudflare-workers-and-pages[bot]]

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