Update Arm references

[riverar]

• Removes obsolete Arm (32-bit) references and warnings
• Adds Arm (64-bit) references

[learn-build-service-prod]

Learn Build status updates of commit 022218f:

✅ Validation status: passed

File	Status	Preview URL	Details
msix-src/desktop/desktop-to-uwp-manual-conversion.md	✅Succeeded

For more details, please refer to the build report.

For any questions, please:

• Try searching the learn.microsoft.com contributor guides
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[riverar]

Or perhaps we align this with https://learn.microsoft.com/en-us/windows/msix/package/create-app-package-with-makeappx-tool