[Crash] Fix crash when searching products in order product selector

[rachelmcr]

Closes: #14085

Description

This fixes a crash caused by fetching products from storage while updating them in the same context on a background thread. This happened while performing a product search in the order form product selector (while adding products to an order).

This also includes a small improvement to the local search, to return results with partial matches to the search term (similar to the remote search method) instead of only exact matches.

How

• Instead of using sharedDerivedStorage (which is storageManager.writerDerivedStorage, meant for writing to storage and used for background updates) we now use storageManager.viewStorage to fetch the products.
• The local search predicate now uses CONTAINS instead of LIKE (to return partial matches).

Steps to reproduce

Note: I was only able to get the app to crash in the simulator. I couldn't reproduce this crash on a device, but as the simulator crash indicates this action is not thread safe.

1. Build and run the app.
2. Go to the Orders tab.
3. Tap "+" to create a new order.
4. Tap "Add Products".
5. Search for a product. Notice that it crashes on _PFAssertSafeMultiThreadedAccess_impl.

Testing information

Test with the same steps as above in this branch and confirm it doesn't crash.

Additional testing:

1. Build and run the app with Xcode 16.
2. Go to the Orders tab.
3. Tap "+" to create a new order.
4. Tap "Add Products".
5. Search for a product using a partial match (e.g. Card when you have a product called Gift Card in the first page of results) and confirm the match is loaded from storage.

Screenshots

Screencast demonstrates the following search scenarios:

• Local results (full match to product name)
• Local results (partial match) + remote results added
• No local results + remote results added
• No local results & no remote results

Simulator.Screen.Recording.-.iPhone.16.Pro.-.2024-10-02.at.17.01.49.mp4

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• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

Reviewer (or Author, in the case of optional code reviews):

Please make sure these conditions are met before approving the PR, or request changes if the PR needs improvement:

• The PR is small and has a clear, single focus, or a valid explanation is provided in the description. If needed, please request to split it into smaller PRs.
• Ensure Adequate Unit Test Coverage: The changes are reasonably covered by unit tests or an explanation is provided in the PR description.
• Manual Testing: The author listed all the tests they ran, including smoke tests when needed (e.g., for refactorings). The reviewer confirmed that the PR works as expected on all devices (phone/tablet) and no regressions are added.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 20.7. This milestone is due in less than 2 days. Please make sure to get it merged by then or assign it to a milestone with a later deadline.

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📲 You can test the changes from this Pull Request in WooCommerce iOS by scanning the QR code below to install the corresponding build.

	App Name	WooCommerce iOS
	Build Number	pr14095-957c6d1
	Version	20.6
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	957c6d1
	App Center Build	WooCommerce - Prototype Builds #11093

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