Fix for Android - Dynamic Updates to CollectionView Header/Footer and Templates Are Not Displayed

[SuthiYuvaraj]

Issue Description:

• Dynamic updates to CollectionView's Header/Footer (both text and views) are not adequately reflected on Android.
• Changes to HeaderTemplate and FooterTemplate are also not applied correctly at runtime.

Root Cause:

• ItemsViewPropertyChanged did not handle updates for HeaderTemplateProperty and FooterTemplateProperty.
• OnBindViewHolder did not account for rendering updated header/footer content or templates.
• Templated headers and footers were not properly managed when the content changed dynamically.

Description of Change

• Added support for HeaderTemplateProperty and FooterTemplateProperty in the ItemsViewPropertyChanged method to ensure runtime changes are detected and processed.
• Updated the OnBindViewHolder method to handle both simple views and string-based headers/footers using SimpleViewHolder.
• Bind the correct templates when a header or footer is templated.
• Enhanced BindTemplatedItemViewHolder to correctly create and bind TemplatedItemViewHolder for HeaderTemplate and FooterTemplate, ensuring updates are accurately reflected in the UI.

Issues Fixed

Fixes #28676

Tested the behaviour on the following platforms

• Android
• Windows
• iOS
• Mac

Output Screenshot

Before Issue Fix	After Issue Fix
HeaderFooterBefore.mov	HeaderFooterFix.mov

[dotnet-policy-service]

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