Marketplace search improvements

[bgrgicak]

Changes proposed in this Pull Request:

This PR improves the search experience in the new Marketplace by showing themes first if there are no extensions, empty search will open the discovery page, and large screens will show 8 results if available.

How to test the changes in this Pull Request:

Using the WooCommerce Testing Instructions Guide, include your detailed testing instructions:

1. Search for a theme that doesn't have extensions as results
2. Confirm that themes are show first and the no-results for extensions components is shown bellow
3. Press enter while focused on the empty search box
4. Confirm that it loads the discovery page
5. Search for a product
6. Expand your window above 1920px
7. Confirm that 8 search results are show if available
8. Reduce your window width bellow 1920px
9. Confirm that 6 items are shown
10. Click on View all
11. Confirm that all results are loaded

Changelog entry

• Automatically create a changelog entry from the details below.

Significance

• Patch
• Minor
• Major

Type

• Fix - Fixes an existing bug
• Add - Adds functionality
• Update - Update existing functionality
• Dev - Development related task
• Tweak - A minor adjustment to the codebase
• Performance - Address performance issues
• Enhancement - Improvement to existing functionality

Message

Comment

In the marketplace show themes first if there are no extensions, empty search will open the discovery page, and large screens will show 8 results if available.

[github-actions]

Test Results Summary

Commit SHA: b27bacf

Test 🧪	Passed ✅	Failed 🚨	Broken 🚧	Skipped ⏭️	Unknown ❔	Total 📊	Duration ⏱️
API Tests	259	0	0	2	0	261	1m 8s
E2E Tests	212	0	0	4	0	216	20m 13s

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To view the full API test report, click here.
To view the full E2E test report, click here.
To view all test reports, visit the WooCommerce Test Reports Dashboard.

[github-actions]

Hi @Dan-Q, @andfinally,

Apart from reviewing the code changes, please make sure to review the testing instructions as well.

You can follow this guide to find out what good testing instructions should look like:
https://github.com/woocommerce/woocommerce/wiki/Writing-high-quality-testing-instructions

[andfinally]

Such a pleasure to see these changes, thank you! 💯 Makes the UI neater and more useful.

[andfinally]

As we're under-strength at the moment, I would be OK with merging this with one review.