[Woo POS] Improve multiple readers alert

[joshheald]

Closes: #13731 Merge after: #13774

Description

This is the last in a series of PRs to improve the card reader connnection screens.

In this PR, the Multiple readers found screen is improved – there's no designs, so I just matched the look and feel of POS.

Steps to reproduce

Use a simulated reader, or two physical readers, to test this.

1. Launch the app
2. Enter the POS
3. Tap Connect your reader
4. Wait for the Do you want to connect screen – if it just auto-connects, tap Reader connected then Disconnect reader and try again
5. Observe that the buttons use the new style
6. Tap Keep searching
7. Observe that the multiple readers screen shows and matches the look and feel of POS.

Testing information

I have tested these on an iPad running iOS 16. No unit tests as it's UI only.

Screenshots

https://github.com/user-attachments/assets/1e5c0721-8796-40f2-b01e-a44c7234e5a8

Note that this video shows an issue at the end where the Multiple Readers View is shown empty after tapping try again on the error. That's an underlying bug, and out of the scope to fix here, but I'll raise an issue.

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• [x] 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.