[Mobile Payments] Show description for trial tap to pay line items

[joshheald]

Description

When a merchant tries out tap to pay on iPhone, we make an order which will remain in their history, even though it gets refunded.

To help merchants identify the order, this PR adds a specific description rather than showing Simple Payment for these payments.

Steps to reproduce

1. Launch the app
2. Navigate to Menu > Payments > Set up/Try out Tap to Pay on iPhone
3. Take a trial payment
4. Find the order in the Orders tab
5. Observe that the item is named Try out Tap to Pay on iPhone

Testing information

Note that Simple Payments is only used for Try out Tap to Pay at present, but I've preserved the previous behaviour of having Simple Payment as the description when no name is provided. This is covered by unit tests.

I have tested the trial payments on an iPhone running iOS 17 and one running iOS 18

Screenshots

try.out.tap.to.pay.label.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.

[joshheald]

@iamgabrielma again not urgent, just fit it in when you can

[wpmobilebot]

📲 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	pr14022-4ac7845
	Version	20.5
	Bundle ID	com.automattic.alpha.woocommerce
	Commit	4ac7845
	App Center Build	WooCommerce - Prototype Builds #10964

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