[iOS] Fix for CollectionView single item horizontal alignment issue when using ItemsLayout with a Footer.

[Tamilarasan-Paranthaman]

Root Cause:

• We had already reset the alignment in the NeedsSingleItemHorizontalAlignmentAdjustment method when a single element was in view. However, we also considered the CollectionView's bottom content inset in that condition, which led to the issue. When a footer was set, its height was added to the bottom content inset. This value did not match the layout attributes' Frame.Top value, and preventing the alignment from being reset.

Description of Change:

• I fixed this issue by removing the CollectionView.ContentInset.Bottom value, as the footer affects the bottom content inset. The top of the first element should align with the top of the CollectionView unless grouping is enabled.
• Additionally, the current implementation only handles the default case; we need to adjust it based on the grouping setting. Since this issue is not related to the customer-reported case, we can log it as a separate bug and address it individually.

Issues Fixed

Fixes #21728

Screenshots

Before Issue Fix	After Issue Fix

[dotnet-policy-service]

Hey there @Tamilarasan-Paranthaman! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[jfversluis]

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[PureWeen]

/azp run

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[PureWeen]

/azp run

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[PureWeen]

Failing tests are unrelated. CI is timing out on templates tests unrelated to this PR