Enable ARM64 submission on MS Store by upgrading WinUI from 2.6.2 to 2.7.1

[veler]

Describe the bug
Unable to publish ARM64 build on the Microsoft Store due to the following issue:

Cause
The issue is caused by WinUI 2.6.X. See microsoft/microsoft-ui-xaml#5768

Fix
The bug has been fixed in WinUI 2.7.1-previewX
Once 2.7.1 stable is release, we should be able to upgrade WinUI in DevToys, and it should be enough to address the issue and re-enable arm64 in MSStore build in the CI. https://github.com/veler/DevToys/blob/347ee0cab5dfa109cdc4794b3b57986e9aaef4ac/ci/azure-pipelines-release.yml#L108